Document and Entity Information Document - shares	3 Months Ended
Document and Entity Information Document - shares	Mar. 31, 2018	May 02, 2018
Document Information [Line Items]
Entity Registrant Name	AMERICAN EQUITY INVESTMENT LIFE HOLDING CO
Entity Central Index Key	0001039828
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		90,095,990

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fixed maturity securities:
Available for sale, at fair value (amortized cost: 2018 - $44,510,813; 2017 - $43,116,759)	$ 45,551,348	$ 45,372,989
Held for investment, at amortized cost (fair value: 2018 - $69,441; 2017 - $76,460)	77,043	77,041
Mortgage loans on real estate	2,699,637	2,665,531
Derivative instruments	847,741	1,568,380
Other investments	481,825	616,764
Total investments	49,657,594	50,300,705
Cash and cash equivalents	723,784	1,434,045
Coinsurance deposits	4,871,912	4,858,289
Accrued investment income	454,519	429,008
Deferred policy acquisition costs	3,039,311	2,714,523
Deferred sales inducements	2,219,597	2,001,892
Deferred income taxes	159,601	38,147
Other assets	175,006	254,127
Total assets	61,301,324	62,030,736
Liabilities:
Policy benefit reserves	56,072,140	56,142,673
Other policy funds and contract claims	280,072	282,884
Notes payable	494,215	494,093
Subordinated debentures	242,667	242,565
Amounts due under repurchase agreements	137,223	0
Income taxes payable	72,191	34,285
Other liabilities	1,455,826	1,984,079
Total liabilities	58,754,334	59,180,579
Stockholders' equity:
Preferred stock, par value $1 per share, 2,000,000 shares authorized, 2018 and 2017 - no shares issued and outstanding	0	0
Common stock, par value $1 per share, 200,000,000 shares authorized; issued and outstanding: 2018 - 89,983,823 shares (excluding 1,814,460 treasury shares); 2017 - 89,331,087 shares (excluding 2,064,727 treasury shares)	89,984	89,331
Additional paid-in capital	798,835	791,446
Accumulated other comprehensive income	399,982	724,599
Retained earnings	1,258,189	1,244,781
Total stockholders' equity	2,546,990	2,850,157
Total liabilities and stockholders' equity	$ 61,301,324	$ 62,030,736

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fixed maturity securities:
Available for sale, amortized cost	$ 44,510,813	$ 43,116,759
Held for investment, fair value	$ 69,441	$ 76,460
Stockholders' equity:
Preferred stock, par value (dollars per share)	$ 1	$ 1
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (dollars per share)	$ 1	$ 1
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	89,983,823	89,331,087
Common stock, shares outstanding	89,983,823	89,331,087
Common stock, shares held in treasury	1,814,460	2,064,727

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Premiums and other considerations	$ 9,053	$ 9,402
Annuity product charges	50,723	43,572
Net investment income	510,784	485,597
Change in fair value of derivatives	(451,083)	386,533
Net realized gains on investments, excluding other than temporary impairment (OTTI) losses	302	2,338
OTTI losses on investments:
Total OTTI losses	(907)	0
Portion of OTTI losses recognized in (from) other comprehensive income	0	(141)
Net OTTI losses recognized in operations	(907)	(141)
Total revenues	118,872	927,301
Benefits and expenses:
Insurance policy benefits and change in future policy benefits	12,094	11,875
Interest sensitive and index product benefits	514,095	419,139
Amortization of deferred sales inducements	100,423	62,325
Change in fair value of embedded derivatives	(867,232)	224,170
Interest expense on notes and loan payable	6,372	7,722
Interest expense on subordinated debentures	3,630	3,336
Amortization of deferred policy acquisition costs	140,639	89,678
Other operating costs and expenses	31,240	27,579
Total benefits and expenses	(58,739)	845,824
Income before income taxes	177,611	81,477
Income tax expense	36,649	27,538
Net income	$ 140,962	$ 53,939
Earnings per common share	$ 1.57	$ 0.61
Earnings per common share - assuming dilution	$ 1.55	$ 0.60
Weighted average common shares outstanding: earnings per common share	90,017,166	88,647,078
Weighted average common shares outstanding: earnings per common share - assuming dilution	91,139,348	89,975,612

Consolidated Statements of Comprehensive Income (Loss) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2018

Mar. 31, 2017

Net income

$ 140,962

$ 53,939

Other comprehensive income (loss):

Change in net unrealized investment gains/losses (1)

^[1]

(572,033)

129,124

Noncredit component of OTTI losses (1)

^[1]

Reclassification of unrealized investment gains/losses to net income (1)

^[1]

(339)

930

Other comprehensive income (loss) before income tax

(572,372)

130,119

Income tax effect related to other comprehensive income (loss)

120,201

(45,542)

Other comprehensive income (loss)

(452,171)

84,577

Comprehensive income (loss)

$ (311,209)

$ 138,516

[1]	Net of related adjustments to amortization of deferred sales inducements and deferred policy acquisition costs.

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Stockholders' equity at beginning of period at Dec. 31, 2016	$ 2,291,595	$ 88,001	$ 770,344	$ 339,966	$ 1,093,284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	53,939				53,939
Other comprehensive income (loss)	84,577			84,577
Share-based compensation	2,403		2,403
Issuance of common stock under compensation plans	3,717	630	3,087
Stockholders' equity at end of period at Mar. 31, 2017	2,436,231	88,631	775,834	424,543	1,147,223
Stockholders' equity at beginning of period at Dec. 31, 2017	2,850,157	89,331	791,446	724,599	1,244,781
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	140,962				140,962
Other comprehensive income (loss)	(452,171)			(452,171)
Implementation of accounting standard related to the reclassification of certain tax effects				127,554	(127,554)
Share-based compensation	3,526		3,526
Issuance of common stock under compensation plans	4,516	653	3,863
Stockholders' equity at end of period at Mar. 31, 2018	$ 2,546,990	$ 89,984	$ 798,835	$ 399,982	$ 1,258,189

Consolidated Statements of Changes in Stockholders' Equity (Parentheticals) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Shares of common stock issued under compensation plans	652,736	629,553

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net income	$ 140,962	$ 53,939
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Interest sensitive and index product benefits	514,095	419,139
Amortization of deferred sales inducements	100,423	62,325
Annuity product charges	(50,723)	(43,572)
Change in fair value of embedded derivatives	(867,232)	224,170
Change in traditional life and accident and health insurance reserves	2,049	726
Policy acquisition costs deferred	(96,562)	(110,574)
Amortization of deferred policy acquisition costs	140,639	89,678
Provision for depreciation and other amortization	900	957
Amortization of discounts and premiums on investments	6,002	2,800
Realized gains (losses) on investments and net OTTI losses recognized in operations	605	(2,197)
Distributions from equity method investments	66	122
Change in fair value of derivatives	450,906	(386,842)
Deferred income taxes	(1,253)	(3,670)
Share-based compensation	3,526	2,403
Change in accrued investment income	(25,511)	(26,371)
Change in income taxes recoverable/payable	37,906	31,161
Change in other assets	(470)	33
Change in other policy funds and contract claims	(4,343)	(6,985)
Change in collateral held for derivatives	(784,932)	233,992
Change in other liabilities	(6,472)	(38,754)
Other	(3,757)	(4,431)
Net cash provided by (used in) operating activities	(443,176)	498,049
Sales, maturities, or repayments of investments:
Fixed maturity securities - available for sale	265,837	517,301
Mortgage loans on real estate	68,017	75,110
Derivative instruments	479,675	349,732
Other investments	153,936	4,868
Acquisitions of investments:
Fixed maturity securities - available for sale	(1,310,985)	(1,216,014)
Mortgage loans on real estate	(101,037)	(100,797)
Derivative instruments	(200,542)	(147,283)
Other investments	(15,131)	(1,550)
Purchases of property, furniture and equipment	(1,099)	(1,402)
Net cash used in investing activities	(661,329)	(520,035)
Financing activities
Receipts credited to annuity and single premium universal life policyholder account balances	1,020,429	1,073,583
Coinsurance deposits	(6,867)	63,746
Return of annuity policyholder account balances	(738,219)	(727,494)
Net proceeds from amounts due under repurchase agreements	137,223	0
Proceeds from issuance of common stock	4,516	3,717
Change in checks in excess of cash balance	(22,838)	(10,084)
Net cash provided by financing activities	394,244	403,468
Increase (decrease) in cash and cash equivalents	(710,261)	381,482
Cash and cash equivalents at beginning of period	1,434,045	791,266
Cash and cash equivalents at end of period	723,784	1,172,748
Cash paid during period for interest:
Interest expense	3,488	18,682
Cash paid during period for income taxes:
Income taxes	0	47
Non-cash operating activity:
Deferral of sales inducements	$ 43,670	$ 65,245

Significant Accounting Policies	3 Months Ended
Significant Accounting Policies	Mar. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Consolidation and Basis of Presentation The accompanying consolidated financial statements of American Equity Investment Life Holding Company ("we", "us" or "our") have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and notes required by GAAP for complete financial statements. The consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly our financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for the three month period ended March 31, 2018 are not necessarily indicative of the results that may be expected for the year ended December 31, 2018. All significant intercompany accounts and transactions have been eliminated. The preparation of financial statements requires the use of management estimates. For further information related to a description of areas of judgment and estimates and other information necessary to understand our financial position and results of operations, refer to the audited consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2017. Adopted Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update ("ASU") related to revenue arising from contracts with customers. This ASU, which replaces most current revenue recognition guidance, including industry specific guidance, prescribes that an entity should recognize revenue to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We adopted this ASU on January 1, 2018. The adoption of this ASU had no impact on our consolidated financial statements as revenues related to insurance contracts and investment contracts are excluded from its scope. In January 2016, the FASB issued an ASU that, among other aspects of recognition, measurement, presentation and disclosure of financial instruments, primarily requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. However, an entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Additionally, it changes the accounting for financial liabilities measured at fair value under the fair value option and eliminates some disclosures regarding fair value of financial assets and liabilities measured at amortized cost. We adopted this ASU on January 1, 2018. The adoption of this ASU had no impact on our consolidated financial statements. In August 2016, the FASB issued an ASU that clarifies how certain cash receipts and cash payments are to be presented and classified in the statement of cash flows. We adopted this ASU on January 1, 2018. The adoption of this ASU resulted in a reclassification of certain cash flows related to equity method investment distributions from investing activities to operating activities within our consolidated statements of cash flows. In February 2018, the FASB issued an ASU that allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 ("Tax Reform"). We adopted this ASU on January 1, 2018. The adoption of this ASU resulted in a reclassification of $128 million between accumulated other comprehensive income and retained earnings within our consolidated balance sheet. New Accounting Pronouncements In February 2016, the FASB issued an ASU that will require recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This ASU affects accounting and disclosure more dramatically for lessees as accounting for lessors is mainly unchanged. This ASU will be effective for us on January 1, 2019, with early adoption permitted. We are in the process of evaluating the impact this guidance may have on our consolidated financial statements. In June 2016, the FASB issued an ASU that significantly changes the impairment model for most financial assets that are measured at amortized cost and certain other instruments from an incurred loss model to an expected loss model that requires these assets be presented at the net amount expected to be collected. In addition, credit losses on available for sale debt securities should be recorded through an allowance account. This ASU will be effective for us on January 1, 2020, with early adoption permitted. While we are still in the process of evaluating the impact this guidance will have on our consolidated financial statements, we believe the new impairment model will lead to earlier recognition of credit losses for our commercial mortgage loans. In March 2017, the FASB issued an ASU that applies to certain callable debt securities where the amortized cost basis is at a premium to the price repayable by the issuer at the earliest call date. Under this guidance, the premium will be amortized to the first call date. This ASU will be effective for us on January 1, 2019, with early adoption permitted. We are in the process of evaluating the impact this guidance may have on our consolidated financial statements. Income Tax Reform As a result of Tax Reform, the federal corporate tax rate was reduced from 35% to 21% effective January 1, 2018.

Fair Values of Financial Instruments

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair Values of Financial Instruments

The following sets forth a comparison of the carrying amounts and fair values of our financial instruments:



	March 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(Dollars in thousands)
Assets
Fixed maturity securities:
Available for sale	$	45,551,348	$	45,551,348	$	45,372,989	$	45,372,989
Held for investment	77,043		69,441		77,041		76,460
Mortgage loans on real estate	2,699,637		2,684,976		2,665,531		2,670,037
Derivative instruments	847,741		847,741		1,568,380		1,568,380
Other investments	481,825		472,642		616,764		605,894
Cash and cash equivalents	723,784		723,784		1,434,045		1,434,045
Coinsurance deposits	4,871,912		4,402,849		4,858,289		4,347,990
Interest rate caps	890		890		415		415
Interest rate swap	427		427		—		—
Counterparty collateral	124,778		124,778		186,108		186,108

Liabilities
Policy benefit reserves	55,713,429		47,137,678		55,786,011		46,344,931
Single premium immediate annuity (SPIA) benefit reserves	279,678		288,991		282,563		292,153
Notes payable	494,215		506,345		494,093		521,800
Subordinated debentures	242,667		229,588		242,565		244,117
Amounts due under repurchase agreements	137,223		137,223		—		—
Interest rate swap	—		—		789		789

Fair value is the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. The objective of a fair value measurement is to determine that price for each financial instrument at each measurement date. We meet this objective using various methods of valuation that include market, income and cost approaches.

We categorize our financial instruments into three levels of fair value hierarchy based on the priority of inputs used in determining fair value. The hierarchy defines the highest priority inputs (Level 1) as quoted prices in active markets for identical assets or liabilities. The lowest priority inputs (Level 3) are our own assumptions about what a market participant would use in determining fair value such as estimated future cash flows. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, a financial instrument's level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the financial instrument. We categorize financial assets and liabilities recorded at fair value in the consolidated balance sheets as follows:


Level 1—	Quoted prices are available in active markets for identical financial instruments as of the reporting date. We do not adjust the quoted price for these financial instruments, even in situations where we hold a large position and a sale could reasonably impact the quoted price.


Level 2—	Quoted prices in active markets for similar financial instruments, quoted prices for identical or similar financial instruments in markets that are not active; and models and other valuation methodologies using inputs other than quoted prices that are observable.

Level 3—

Models and other valuation methodologies using significant inputs that are unobservable for financial instruments and include situations where there is little, if any, market activity for the financial instrument. The inputs into the determination of fair value require significant management judgment or estimation. Financial instruments that are included in Level 3 are securities for which no market activity or data exists and for which we used discounted expected future cash flows with our own assumptions about what a market participant would use in determining fair value.

Transfers of securities among the levels occur at times and depend on the type of inputs used to determine fair value of each security. There were no transfers between levels during any period presented.

Our assets and liabilities which are measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 are presented below based on the fair value hierarchy levels:



	Total Fair Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(Dollars in thousands)
March 31, 2018
Assets
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,433	$	5,541	$	5,892	$	—
United States Government sponsored agencies	1,270,106		—		1,270,106		—
United States municipalities, states and territories	4,137,005		—		4,137,005		—
Foreign government obligations	231,671		—		231,671		—
Corporate securities	29,584,128		375		29,583,753		—
Residential mortgage backed securities	1,102,609		—		1,102,609		—
Commercial mortgage backed securities	5,596,882		—		5,596,882		—
Other asset backed securities	3,617,514		—		3,617,514		—
Other investments: equity securities	157,431		150,000		7,431		—
Derivative instruments	847,741		—		847,741		—
Cash and cash equivalents	723,784		723,784		—		—
Interest rate caps	890		—		890		—
Interest rate swap	427		—		427		—
Counterparty collateral	124,778		—		124,778		—
	$	47,406,399	$	879,700	$	46,526,699	$	—
Liabilities
Fixed index annuities - embedded derivatives	$	8,233,557	$	—	$	—	$	8,233,557
	$	8,233,557	$	—	$	—	$	8,233,557

December 31, 2017
Assets
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,876	$	5,640	$	6,236	$	—
United States Government sponsored agencies	1,305,017		—		1,305,017		—
United States municipalities, states and territories	4,166,812		—		4,166,812		—
Foreign government obligations	239,360		—		239,360		—
Corporate securities	29,878,971		5		29,878,966		—
Residential mortgage backed securities	1,105,567		—		1,105,567		—
Commercial mortgage backed securities	5,544,850		—		5,544,850		—
Other asset backed securities	3,120,536		—		3,120,536		—
Other investments: equity securities, available for sale	292,429		285,000		7,429		—
Derivative instruments	1,568,380		—		1,568,380		—
Cash and cash equivalents	1,434,045		1,434,045		—		—
Interest rate caps	415		—		415		—
Counterparty collateral	186,108		—		186,108		—
	$	48,854,366	$	1,724,690	$	47,129,676	$	—
Liabilities
Interest rate swap	$	789	$	—	$	789	$	—
Fixed index annuities - embedded derivatives	8,790,427		—		—		8,790,427
	$	8,791,216	$	—	$	789	$	8,790,427

The following methods and assumptions were used in estimating the fair values of financial instruments during the periods presented in these consolidated financial statements.

Fixed maturity securities and equity securities

The fair values of fixed maturity securities and equity securities in an active and orderly market are determined by utilizing independent pricing services. The independent pricing services incorporate a variety of observable market data in their valuation techniques, including:


•	reported trading prices,


•	benchmark yields,


•	broker-dealer quotes,


•	benchmark securities,


•	bids and offers,


•	credit ratings,


•	relative credit information, and


•	other reference data.

The independent pricing services also take into account perceived market movements and sector news, as well as a security's terms and conditions, including any features specific to that issue that may influence risk and marketability. Depending on the security, the priority of the use of observable market inputs may change as some observable market inputs may not be relevant or additional inputs may be necessary.

The independent pricing services provide quoted market prices when available. Quoted prices are not always available due to market inactivity. When quoted market prices are not available, the third parties use yield data and other factors relating to instruments or securities with similar characteristics to determine fair value for securities that are not actively traded. We generally obtain one value from our primary external pricing service. In situations where a price is not available from this service, we may obtain quotes or prices from additional parties as needed. Market indices of similar rated asset class spreads are considered for valuations and broker indications of similar securities are compared. Inputs used by the broker include market information, such as yield data and other factors relating to instruments or securities with similar characteristics. Valuations and quotes obtained from third party commercial pricing services are non-binding and do not represent quotes on which one may execute the disposition of the assets.

We validate external valuations at least quarterly through a combination of procedures that include the evaluation of methodologies used by the pricing services, analytical reviews and performance analysis of the prices against trends, and maintenance of a securities watch list. Additionally, as needed we utilize discounted cash flow models or perform independent valuations on a case-by-case basis using inputs and assumptions similar to those used by the pricing services. Although we do identify differences from time to time as a result of these validation procedures, we did not make any significant adjustments as of March 31, 2018 and December 31, 2017.

Mortgage loans on real estate

Mortgage loans on real estate are not measured at fair value on a recurring basis. The fair values of mortgage loans on real estate are calculated using discounted expected cash flows using competitive market interest rates currently being offered for similar loans. The fair values of impaired mortgage loans on real estate that we have considered to be collateral dependent are based on the fair value of the real estate collateral (based on appraised values) less estimated costs to sell. The inputs utilized to determine fair value of all mortgage loans are unobservable market data (competitive market interest rates); therefore, fair value of mortgage loans falls into Level 3 in the fair value hierarchy.

Derivative instruments

The fair values of derivative instruments, primarily call options, are based upon the amount of cash that we will receive to settle each derivative instrument on the reporting date. These amounts are determined by our investment team using industry accepted valuation models and are adjusted for the nonperformance risk of each counterparty net of any collateral held. Inputs include market volatility and risk free interest rates and are used in income valuation techniques in arriving at a fair value for each option contract. The nonperformance risk for each counterparty is based upon its credit default swap rate. We have no performance obligations related to the call options purchased to fund our fixed index annuity policy liabilities.

Other investments

Equity securities are the only financial instruments included in other investments that are measured at fair value on a recurring basis (see determination of fair value above). Financial instruments included in other investments that are not measured at fair value on a recurring basis are policy loans, equity method investments and company owned life insurance ("COLI"). We have not attempted to determine the fair values associated with our policy loans, as we believe any differences between carrying values and the fair values afforded these instruments are immaterial to our consolidated financial position and, accordingly, the cost to provide such disclosure does not justify the benefit to be derived. The fair values of our equity method investments are obtained from third parties and determined by calculating the present value of future cash flows discounted by a risk free rate, a risk spread and a liquidity discount. As the risk spread and liquidity discount are unobservable market inputs, the fair value of our equity method investments falls within Level 3 of the fair value hierarchy. The fair value of our COLI approximates the cash surrender value of the policies and falls within Level 2 of the fair value hierarchy.

Cash and cash equivalents

Amounts reported in the consolidated balance sheets for these instruments are reported at their historical cost which approximates fair value due to the nature of the assets assigned to this category.

Interest rate swap and caps

The fair values of our pay fixed/receive variable interest rate swap and our interest rate caps are obtained from third parties and are determined by discounting expected future cash flows using a projected London Interbank Offered Rate ("LIBOR") for the term of the swap and caps.

Counterparty collateral

Amounts reported in other assets in the consolidated balance sheets for these instruments are reported at their historical cost which approximates fair value due to the nature of the assets assigned to this category.

Policy benefit reserves, coinsurance deposits and SPIA benefit reserves

The fair values of the liabilities under contracts not involving significant mortality or morbidity risks (principally deferred annuities), are stated at the cost we would incur to extinguish the liability (i.e., the cash surrender value) as these contracts are generally issued without an annuitization date. The coinsurance deposits related to the annuity benefit reserves have fair values determined in a similar fashion. For period-certain annuity benefit contracts, the fair value is determined by discounting the benefits at the interest rates currently in effect for newly issued immediate annuity contracts. We are not required to and have not estimated the fair value of the liabilities under contracts that involve significant mortality or morbidity risks, as these liabilities fall within the definition of insurance contracts that are exceptions from financial instruments that require disclosures of fair value. Policy benefit reserves, coinsurance deposits and SPIA benefit reserves are not measured at fair value on a recurring basis. All of the fair values presented within these categories fall within Level 3 of the fair value hierarchy as most of the inputs are unobservable market data.

Notes payable

The fair values of our senior unsecured notes are based upon pricing matrices developed by a third party pricing service when quoted market prices are not available and are categorized as Level 2 within the fair value hierarchy. Notes payable are not remeasured at fair value on a recurring basis.

Subordinated debentures

Fair values for subordinated debentures are estimated using discounted cash flow calculations based principally on observable inputs including our incremental borrowing rates, which reflect our credit rating, for similar types of borrowings with maturities consistent with those remaining for the debt being valued. These fair values are categorized as Level 2 within the fair value hierarchy. Subordinated debentures are not measured at fair value on a recurring basis.

Amounts due under repurchase agreements

The amounts reported in the consolidated balance sheets for short term indebtedness under repurchase agreements with variable interest rates approximate their fair values.

Fixed index annuities - embedded derivatives

We estimate the fair value of the embedded derivative component of our fixed index annuity policy benefit reserves at each valuation date by (i) projecting policy contract values and minimum guaranteed contract values over the expected lives of the contracts and (ii) discounting the excess of the projected contract value amounts at the applicable risk free interest rates adjusted for our nonperformance risk related to those liabilities. The projections of policy contract values are based on our best estimate assumptions for future policy growth and future policy decrements. Our best estimate assumptions for future policy growth include assumptions for the expected index credit on the next policy anniversary date which are derived from the fair values of the underlying call options purchased to fund such index credits and the expected costs of annual call options we will purchase in the future to fund index credits beyond the next policy anniversary. The projections of minimum guaranteed contract values include the same best estimate assumptions for policy decrements as were used to project policy contract values.

Within this determination we have the following significant unobservable inputs: 1) the expected cost of annual call options we will purchase in the future to fund index credits beyond the next policy anniversary and 2) our best estimates for future policy decrements, primarily lapse, partial withdrawal and mortality rates. As of March 31, 2018 and December 31, 2017, we utilized an estimate of 3.10% for the expected cost of annual call options, which is based on estimated long-term account value growth and a historical review of our actual option costs.

Our best estimate assumptions for lapse, partial withdrawal and mortality rates are based on our actual experience and our outlook as to future expectations for such assumptions. These assumptions, which are consistent with the assumptions used in calculating deferred policy acquisition costs and deferred sales inducements, are reviewed on a quarterly basis and are revised as our experience develops and/or as future expectations change. Our mortality rate assumptions are based on 65% of the 1983 Basic Annuity Mortality Tables. The following table presents average lapse rate and partial withdrawal rate assumptions, by contract duration, used in estimating the fair value of the embedded derivative component of our fixed index annuity policy benefit reserves at each reporting date:



	Average Lapse Rates		Average Partial Withdrawal Rates
Contract Duration (Years)	March 31, 2018	December 31, 2017	March 31, 2018	December 31, 2017
1 - 5	2.11%	1.83%	3.33%	3.32%
6 - 10	7.30%	7.01%	3.33%	3.32%
11 - 15	11.33%	11.31%	3.34%	3.34%
16 - 20	11.91%	11.96%	3.24%	3.20%
20+	11.58%	11.62%	3.21%	3.20%

Lapse rates are generally expected to increase as surrender charge percentages decrease. Lapse expectations reflect a significant increase in the year in which the surrender charge period on a contract ends.

The following table provides a reconciliation of the beginning and ending balances for our Level 3 liabilities, which are measured at fair value on a recurring basis using significant unobservable inputs for the three months ended March 31, 2018 and 2017:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Fixed index annuities - embedded derivatives
Beginning balance	$	8,790,427		$	6,563,288
Premiums less benefits	549,153			411,502
Change in fair value, net	(1,106,023		)	76,210
Ending balance	$	8,233,557		$	7,051,000

The fair value of our fixed index annuities embedded derivatives is net of coinsurance ceded of $529.6 million and $539.7 million as of March 31, 2018 and December 31, 2017, respectively. Change in fair value, net for each period in our embedded derivatives is included in change in fair value of embedded derivatives in the unaudited consolidated statements of operations.

Certain derivatives embedded in our fixed index annuity contracts are our most significant financial instrument measured at fair value that are categorized as Level 3 in the fair value hierarchy. The contractual obligations for future annual index credits within our fixed index annuity contracts are treated as a "series of embedded derivatives" over the expected life of the applicable contracts. We estimate the fair value of these embedded derivatives at each valuation date by the method described above under fixed index annuities - embedded derivatives. The projections of minimum guaranteed contract values include the same best estimate assumptions for policy decrements as were used to project policy contract values.

The most sensitive assumption in determining policy liabilities for fixed index annuities is the rates used to discount the excess projected contract values. As indicated above, the discount rate reflects our nonperformance risk. If the discount rates used to discount the excess projected contract values at March 31, 2018, were to increase by 100 basis points, the fair value of the embedded derivatives would decrease by $529.0 million recorded through operations as a decrease in the change in fair value of embedded derivatives and there would be a corresponding decrease of $321.0 million to our combined balance for deferred policy acquisition costs and deferred sales inducements recorded through operations as an increase in amortization of deferred policy acquisition costs and deferred sales inducements. A decrease by 100 basis points in the discount rate used to discount the excess projected contract values would increase the fair value of the embedded derivatives by $588.5 million recorded through operations as an increase in the change in fair value of embedded derivatives and there would be a corresponding increase of $340.9 million to our combined balance for deferred policy acquisition costs and deferred sales inducements recorded through operations as a decrease in amortization of deferred policy acquisition costs and deferred sales inducements.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Investments

3 Months Ended

Mar. 31, 2018

Investments [Abstract]

Investments

At March 31, 2018 and December 31, 2017, the amortized cost and fair value of fixed maturity securities were as follows:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
March 31, 2018
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,696	$	110	$	(373	)	$	11,433
United States Government sponsored agencies	1,308,312		21,134		(59,340		)	1,270,106
United States municipalities, states and territories	3,853,098		296,762		(12,855		)	4,137,005
Foreign government obligations	227,617		8,502		(4,448		)	231,671
Corporate securities	28,801,351		1,186,607		(403,830		)	29,584,128
Residential mortgage backed securities	1,044,032		65,581		(7,004		)	1,102,609
Commercial mortgage backed securities	5,685,290		33,098		(121,506		)	5,596,882
Other asset backed securities	3,579,417		52,730		(14,633		)	3,617,514
	$	44,510,813	$	1,664,524	$	(623,989	)	$	45,551,348
Held for investment:
Corporate security	$	77,043	$	—	$	(7,602	)	$	69,441

December 31, 2017
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,861	$	162	$	(147	)	$	11,876
United States Government sponsored agencies	1,308,290		28,457		(31,730		)	1,305,017
United States municipalities, states and territories	3,804,360		366,048		(3,596		)	4,166,812
Foreign government obligations	228,214		13,171		(2,025		)	239,360
Corporate securities	28,127,653		1,897,005		(145,687		)	29,878,971
Residential mortgage backed securities	1,028,484		79,554		(2,471		)	1,105,567
Commercial mortgage backed securities	5,531,922		82,768		(69,840		)	5,544,850
Other asset backed securities	3,075,975		57,966		(13,405		)	3,120,536
	$	43,116,759	$	2,525,131	$	(268,901	)	$	45,372,989
Held for investment:
Corporate security	$	77,041	$	—	$	(581	)	$	76,460

Other investments: equity securities, available for sale:
Finance, insurance, and real estate	$	292,429	$	—	$	—		$	292,429

At March 31, 2018, 37% of our fixed income securities have call features, of which 2.7% ($1.2 billion) were subject to call redemption and another 0.2% ($111.2 million) will become subject to call redemption during the next twelve months. Approximately 74% of our fixed income securities that have call features are not callable until within six months of their stated maturities.

The amortized cost and fair value of fixed maturity securities at March 31, 2018, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. All of our mortgage and other asset backed securities provide for periodic payments throughout their lives and are shown below as separate lines.



	Available for sale				Held for investment
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	218,825	$	223,487	$	—	$	—
Due after one year through five years	5,615,360		5,673,765		—		—
Due after five years through ten years	10,439,109		10,428,466		—		—
Due after ten years through twenty years	9,188,746		9,774,966		—		—
Due after twenty years	8,740,034		9,133,659		77,043		69,441
	34,202,074		35,234,343		77,043		69,441
Residential mortgage backed securities	1,044,032		1,102,609		—		—
Commercial mortgage backed securities	5,685,290		5,596,882		—		—
Other asset backed securities	3,579,417		3,617,514		—		—
	$	44,510,813	$	45,551,348	$	77,043	$	69,441

Net unrealized gains on available for sale fixed maturity securities reported as a separate component of stockholders' equity were comprised of the following:



	March 31, 2018			December 31, 2017
	(Dollars in thousands)
Net unrealized gains on available for sale fixed maturity securities	$	1,040,535		$	2,256,230
Adjustments for assumed changes in amortization of deferred policy acquisition costs and deferred sales inducements	(562,755		)	(1,206,078		)
Deferred income tax valuation allowance reversal	22,534			22,534
Deferred income tax expense (a)	(100,332		)	(348,087		)
Net unrealized gains reported as accumulated other comprehensive income	$	399,982		$	724,599


(a)	December 31, 2017 includes $128 million related to the impact of Tax Reform that was reclassified between accumulated other comprehensive income and retained earnings within our consolidated balance sheet during the first quarter of 2018. For more information regarding the reclassification, see Note 1 to our unaudited consolidated financial statements.

The National Association of Insurance Commissioners ("NAIC") assigns designations to fixed maturity securities. These designations range from Class 1 (highest quality) to Class 6 (lowest quality). In general, securities are assigned a designation based upon the ratings they are given by the Nationally Recognized Statistical Rating Organizations ("NRSRO’s"). The NAIC designations are utilized by insurers in preparing their annual statutory statements. NAIC Class 1 and 2 designations are considered "investment grade" while NAIC Class 3 through 6 designations are considered "non-investment grade." Based on the NAIC designations, we had 97% of our fixed maturity portfolio rated investment grade at both March 31, 2018 and December 31, 2017, respectively.

The following table summarizes the credit quality, as determined by NAIC designation, of our fixed maturity portfolio as of the dates indicated:



	March 31, 2018				December 31, 2017
NAIC Designation	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
1	$	27,142,276	$	27,984,297	$	26,669,427	$	28,274,379
2	15,897,296		16,147,267		15,198,551		15,869,219
3	1,350,395		1,316,146		1,161,737		1,157,420
4	170,754		145,085		134,838		117,542
5	17,108		19,926		17,015		20,927
6	10,027		8,068		12,232		9,962
	$	44,587,856	$	45,620,789	$	43,193,800	$	45,449,449

The following table shows our investments' gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities (consisting of 1,902 and 955 securities, respectively) have been in a continuous unrealized loss position, at March 31, 2018 and December 31, 2017:



	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(Dollars in thousands)
March 31, 2018
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	3,193	$	(50	)	$	6,380	$	(323	)	$	9,573	$	(373	)
United States Government sponsored agencies	74,632		(1,513		)	932,691		(57,827		)	1,007,323		(59,340		)
United States municipalities, states and territories	224,928		(5,000		)	124,097		(7,855		)	349,025		(12,855		)
Foreign government obligations	127,620		(2,442		)	12,297		(2,006		)	139,917		(4,448		)
Corporate securities:
Finance, insurance and real estate	1,980,979		(46,008		)	599,683		(48,915		)	2,580,662		(94,923		)
Manufacturing, construction and mining	1,378,585		(29,518		)	229,805		(17,840		)	1,608,390		(47,358		)
Utilities and related sectors	1,830,012		(41,549		)	239,209		(18,121		)	2,069,221		(59,670		)
Wholesale/retail trade	755,307		(16,446		)	173,229		(16,809		)	928,536		(33,255		)
Services, media and other	3,498,221		(85,932		)	855,680		(82,692		)	4,353,901		(168,624		)
Residential mortgage backed securities	286,561		(4,535		)	24,870		(2,469		)	311,431		(7,004		)
Commercial mortgage backed securities	2,495,283		(43,167		)	1,310,142		(78,339		)	3,805,425		(121,506		)
Other asset backed securities	797,174		(6,376		)	187,857		(8,257		)	985,031		(14,633		)
	$	13,452,495	$	(282,536	)	$	4,695,940	$	(341,453	)	$	18,148,435	$	(623,989	)
Held for investment:
Corporate security:
Insurance	$	—	$	—		$	69,441	$	(7,602	)	$	69,441	$	(7,602	)

December 31, 2017
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	1,565	$	(10	)	$	6,731	$	(137	)	$	8,296	$	(147	)
United States Government sponsored agencies	44,794		(180		)	958,965		(31,550		)	1,003,759		(31,730		)
United States municipalities, states and territories	44,736		(128		)	128,499		(3,468		)	173,235		(3,596		)
Foreign government obligations	49,663		(337		)	12,625		(1,688		)	62,288		(2,025		)
Corporate securities:
Finance, insurance and real estate	456,244		(5,135		)	600,655		(28,043		)	1,056,899		(33,178		)
Manufacturing, construction and mining	222,985		(3,475		)	231,196		(10,849		)	454,181		(14,324		)
Utilities and related sectors	395,183		(4,099		)	249,416		(8,901		)	644,599		(13,000		)
Wholesale/retail trade	152,941		(1,249		)	178,635		(11,371		)	331,576		(12,620		)
Services, media and other	729,124		(19,000		)	891,654		(53,565		)	1,620,778		(72,565		)
Residential mortgage backed securities	39,771		(387		)	32,917		(2,084		)	72,688		(2,471		)
Commercial mortgage backed securities	1,096,757		(10,385		)	1,306,437		(59,455		)	2,403,194		(69,840		)
Other asset backed securities	765,531		(3,499		)	217,595		(9,906		)	983,126		(13,405		)
	$	3,999,294	$	(47,884	)	$	4,815,325	$	(221,017	)	$	8,814,619	$	(268,901	)
Held for investment:
Corporate security:
Insurance	$	—	$	—		$	76,460	$	(581	)	$	76,460	$	(581	)

Based on the results of our process for evaluating available for sale securities in unrealized loss positions for other than temporary impairments, which is discussed in detail later in this footnote, we have determined that the unrealized losses on the securities in the preceding table are temporary. The unrealized losses at March 31, 2018 are principally related to timing of the purchases of these securities, which carry less yield than those available at March 31, 2018.

Approximately 88% and 83% of the unrealized losses on fixed maturity securities shown in the above table for March 31, 2018 and December 31, 2017, respectively, are on securities that are rated investment grade, defined as being the highest two NAIC designations. All of the fixed maturity securities with unrealized losses are current with respect to the payment of principal and interest.

Changes in net unrealized gains on investments for the three months ended March 31, 2018 and 2017 are as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Fixed maturity securities held for investment carried at amortized cost	$	(7,021	)	$	(1,976	)
Investments carried at fair value:
Fixed maturity securities, available for sale	$	(1,215,695	)	$	281,094
Equity securities, available for sale	—			(13		)
	(1,215,695		)	281,081
Adjustment for effect on other balance sheet accounts:
Deferred policy acquisition costs and deferred sales inducements	643,323			(150,962		)
Deferred income tax asset/liability	120,201			(45,542		)
	763,524			(196,504		)
Change in net unrealized gains on investments carried at fair value	$	(452,171	)	$	84,577

Proceeds from sales of available for sale securities for the three months ended March 31, 2018 and 2017 were $85.5 million and $186.5 million, respectively. Scheduled principal repayments, calls and tenders for available for sale fixed maturity securities for the three months ended March 31, 2018 and 2017 were $180.4 million and $330.8 million, respectively.

Realized gains and losses on sales are determined on the basis of specific identification of investments based on the trade date. Net realized gains on investments, excluding net OTTI losses for the three months ended March 31, 2018 and 2017, are as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Available for sale fixed maturity securities:
Gross realized gains	$	1,382		$	5,572
Gross realized losses	(2,102		)	(3,563		)
	(720		)	2,009

Other investments:
Gain on sale of real estate	—			29

Mortgage loans on real estate:
Decrease in allowance for credit losses	300			300
Recovery of specific allowance	722			—
	1,022			300
	$	302		$	2,338

Losses on available for sale fixed maturity securities were realized primarily due to strategies to reposition the fixed maturity security portfolio that result in improved net investment income, credit risk or duration profiles as they pertain to our asset liability management.

We review and analyze all investments on an ongoing basis for changes in market interest rates and credit deterioration. This review process includes analyzing our ability to recover the amortized cost basis of each investment that has a fair value that is materially lower than its amortized cost and requires a high degree of management judgment and involves uncertainty. The evaluation of securities for other than temporary impairments is a quantitative and qualitative process, which is subject to risks and uncertainties.

We have a policy and process to identify securities that could potentially have impairments that are other than temporary. This process involves monitoring market events and other items that could impact issuers. The evaluation includes but is not limited to such factors as:


•	the length of time and the extent to which the fair value has been less than amortized cost or cost;


•	whether the issuer is current on all payments and all contractual payments have been made as agreed;


•	the remaining payment terms and the financial condition and near-term prospects of the issuer;


•	the lack of ability to refinance due to liquidity problems in the credit market;


•	the fair value of any underlying collateral;


•	the existence of any credit protection available;


•	our intent to sell and whether it is more likely than not we would be required to sell prior to recovery for debt securities;


•	consideration of rating agency actions; and


•	changes in estimated cash flows of mortgage and asset backed securities.

We determine whether other than temporary impairment losses should be recognized for debt securities by assessing all facts and circumstances surrounding each security. Where the decline in fair value of debt securities is attributable to changes in market interest rates or to factors such as market volatility, liquidity and spread widening, and we anticipate recovery of all contractual or expected cash flows, we do not consider these investments to be other than temporarily impaired because we do not intend to sell these investments and it is not more likely than not we will be required to sell these investments before a recovery of amortized cost, which may be maturity.

If we intend to sell a debt security or if it is more likely than not that we will be required to sell a debt security before recovery of its amortized cost basis, other than temporary impairment has occurred and the difference between amortized cost and fair value will be recognized as a loss in operations.

If we do not intend to sell and it is not more likely than not we will be required to sell the debt security but also do not expect to recover the entire amortized cost basis of the security, an impairment loss would be recognized in operations in the amount of the expected credit loss. We determine the amount of expected credit loss by calculating the present value of the cash flows expected to be collected discounted at each security's acquisition yield based on our consideration of whether the security was of high credit quality at the time of acquisition. The difference between the present value of expected future cash flows and the amortized cost basis of the security is the amount of credit loss recognized in operations. The remaining amount of the other than temporary impairment is recognized in other comprehensive income (loss).

The determination of the credit loss component of a mortgage backed security is based on a number of factors. The primary consideration in this evaluation process is the issuer's ability to meet current and future interest and principal payments as contractually stated at time of purchase. Our review of these securities includes an analysis of the cash flow modeling under various default scenarios considering independent third party benchmarks, the seniority of the specific tranche within the structure of the security, the composition of the collateral and the actual default, loss severity and prepayment experience exhibited. With the input of third party assumptions for default projections, loss severity and prepayment expectations, we evaluate the cash flow projections to determine whether the security is performing in accordance with its contractual obligation.

We utilize the models from a leading structured product software specialist serving institutional investors. These models incorporate each security's seniority and cash flow structure. In circumstances where the analysis implies a potential for principal loss at some point in the future, we use the "best estimate" cash flow projection discounted at the security's effective yield at acquisition to determine the amount of our potential credit loss associated with this security. The discounted expected future cash flows equates to our expected recovery value. Any shortfall of the expected recovery when compared to the amortized cost of the security will be recorded as the credit loss component of other than temporary impairment.

The cash flow modeling is performed on a security-by-security basis and incorporates actual cash flows on the residential mortgage backed securities through the current period, as well as the projection of remaining cash flows using a number of assumptions including default rates, prepayment rates and loss severity rates. The default curves we use are tailored to the Prime or Alt-A residential mortgage backed securities that we own, which assume lower default rates and loss severity for Prime securities versus Alt-A securities. These default curves are scaled higher or lower depending on factors such as current underlying mortgage loan performance, rating agency loss projections, loan to value ratios, geographic diversity, as well as other appropriate considerations.

The following table presents the range of significant assumptions used to determine the credit loss component of other than temporary impairments we have recognized on residential mortgage backed securities for the three months ended March 31, 2017, which are all senior level tranches within the structure of the securities:



		Discount Rate				Default Rate				Loss Severity
Sector	Vintage	Min		Max		Min		Max		Min		Max
Three months ended March 31, 2017
Prime	2005	7.7	%	7.7	%	8	%	8	%	50	%	50	%
	2007	6.2	%	6.3	%	15	%	18	%	50	%	60	%

The determination of the credit loss component of a corporate bond (including redeemable preferred stocks) is based on the underlying financial performance of the issuer and their ability to meet their contractual obligations. Considerations in our evaluation include, but are not limited to, credit rating changes, financial statement and ratio analysis, changes in management, significant changes in credit spreads, breaches of financial covenants and a review of the economic outlook for the industry and markets in which they trade. In circumstances where an issuer appears unlikely to meet its future obligation, or the security's price decline is deemed other than temporary, an estimate of credit loss is determined. Credit loss is calculated using default probabilities as derived from the credit default swaps markets in conjunction with recovery rates derived from independent third party analysis or a best estimate of credit loss. This credit loss rate is then incorporated into a present value calculation based on an expected principal loss in the future discounted at the yield at the date of purchase and compared to amortized cost to determine the amount of credit loss associated with the security.

In addition, for debt securities which we do not intend to sell and it is not more likely than not we will be required to sell, but our intent changes due to changes or events that could not have been reasonably anticipated, an other than temporary impairment charge is recognized. Once an impairment charge has been recorded, we then continue to review the other than temporarily impaired securities for appropriate valuation on an ongoing basis. Unrealized losses may be recognized in future periods through a charge to earnings should we later conclude that the decline in fair value below amortized cost is other than temporary pursuant to our accounting policy described above. The use of different methodologies and assumptions to determine the fair value of investments and the timing and amount of impairments may have a material effect on the amounts presented in our consolidated financial statements.

The following table summarizes other than temporary impairments for the three months ended March 31, 2018 and 2017, by asset type:



	Number of Securities	Total OTTI Losses			Portion of OTTI Losses Recognized in (from) Other Comprehensive Income			Net OTTI Losses Recognized in Operations
		(Dollars in thousands)
Three months ended March 31, 2018
Fixed maturity securities, available for sale:
Corporate securities:
Consumer discretionary	1	$	(907	)	$	—		$	(907	)

Three months ended March 31, 2017
Fixed maturity securities, available for sale:
Residential mortgage backed securities	3	$	—		$	(141	)	$	(141	)

The cumulative portion of other than temporary impairments determined to be credit losses which have been recognized in operations for debt securities are summarized as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Cumulative credit loss at beginning of period	$	(157,066	)	$	(166,375	)
Credit losses on securities for which OTTI has not previously been recognized	(907		)	—
Additional credit losses on securities for which OTTI has previously been recognized	—			(141		)
Accumulated losses on securities that were disposed of during the period	3,900			13,939
Cumulative credit loss at end of period	$	(154,073	)	$	(152,577	)

The following table summarizes the cumulative noncredit portion of OTTI and the change in fair value since recognition of OTTI, both of which were recognized in other comprehensive income, by major type of security, for securities that are part of our investment portfolio at March 31, 2018 and December 31, 2017:



	Amortized Cost		OTTI Recognized in Other Comprehensive Income			Change in Fair Value Since OTTI was Recognized			Fair Value
	(Dollars in thousands)
March 31, 2018
Fixed maturity securities, available for sale:
Corporate securities	$	17,947	$	(3,700	)	$	10,012		$	24,259
Residential mortgage backed securities	282,835		(168,355		)	198,719			313,199
Other asset backed securities	4,567		(1,356		)	(1,631		)	1,580
	$	305,349	$	(173,411	)	$	207,100		$	339,038
December 31, 2017
Fixed maturity securities, available for sale:
Corporate securities	$	13,015	$	(4,263	)	$	10,739		$	19,491
Residential mortgage backed securities	297,582		(168,355		)	201,620			330,847
Other asset backed securities	4,567		(1,356		)	(1,875		)	1,336
	$	315,164	$	(173,974	)	$	210,484		$	351,674

Mortgage Loans on Real Estate

3 Months Ended

Mar. 31, 2018

Mortgage Loans on Real Estate [Abstract]

Mortgage Loans on Real Estate

Our mortgage loan portfolio is summarized in the following table. There were commitments outstanding of $51.7 million at March 31, 2018.



	March 31, 2018			December 31, 2017
	(Dollars in thousands)
Principal outstanding	$	2,707,352		$	2,674,315
Loan loss allowance	(6,496		)	(7,518		)
Deferred prepayment fees	(1,219		)	(1,266		)
Carrying value	$	2,699,637		$	2,665,531

The portfolio consists of commercial mortgage loans collateralized by the related properties and diversified as to property type, location and loan size. Our mortgage lending policies establish limits on the amount that can be loaned to one borrower and other criteria to attempt to reduce the risk of default. The mortgage loan portfolio is summarized by geographic region and property type as follows:



	March 31, 2018				December 31, 2017
	Principal		Percent		Principal		Percent
	(Dollars in thousands)
Geographic distribution
East	$	563,593	20.8	%	$	548,067	20.5	%
Middle Atlantic	166,782		6.2	%	163,485		6.1	%
Mountain	317,872		11.7	%	308,486		11.5	%
New England	12,146		0.5	%	12,265		0.5	%
Pacific	482,593		17.8	%	466,030		17.4	%
South Atlantic	613,999		22.7	%	609,736		22.8	%
West North Central	315,339		11.6	%	324,808		12.2	%
West South Central	235,028		8.7	%	241,438		9.0	%
	$	2,707,352	100.0	%	$	2,674,315	100.0	%
Property type distribution
Office	$	270,066	10.0	%	$	283,926	10.6	%
Medical Office	32,902		1.2	%	34,338		1.3	%
Retail	1,051,749		38.8	%	1,040,028		38.9	%
Industrial/Warehouse	703,892		26.0	%	677,770		25.3	%
Apartment	471,097		17.4	%	462,897		17.3	%
Mixed use/other	177,646		6.6	%	175,356		6.6	%
	$	2,707,352	100.0	%	$	2,674,315	100.0	%

Our financing receivables currently consist of one portfolio segment which is our commercial mortgage loan portfolio. These are mortgage loans with collateral consisting of commercial real estate and borrowers consisting mostly of limited liability partnerships or limited liability corporations.

We evaluate our mortgage loan portfolio for the establishment of a loan loss allowance by specific identification of impaired loans and the measurement of an estimated loss for each individual loan identified. A mortgage loan is impaired when it is probable that we will be unable to collect all amounts due according to the contractual terms of the loan agreement. If we determine that the value of any specific mortgage loan is impaired, the carrying amount of the mortgage loan will be reduced to its fair value, based upon the present value of expected future cash flows from the loan discounted at the loan's effective interest rate, or the fair value of the underlying collateral less estimated costs to sell.

In addition, we analyze the mortgage loan portfolio for the need of a general loan allowance for probable losses on all other loans on a quantitative and qualitative basis. The amount of the general loan allowance is based upon management's evaluation of the collectability of the loan portfolio, historical loss experience, delinquencies, credit concentrations, underwriting standards and national and local economic conditions.

We rate each of the mortgage loans in our portfolio based on factors such as historical operating performance, loan to value ratio and economic outlook, among others. We calculate a loss factor to apply to each rating based on historical losses we have recognized in our mortgage loan portfolio. We apply the loss factors to the total principal outstanding within each rating category to determine an appropriate estimate of the general loan loss allowance. We also assess the portfolio qualitatively and apply a loss rate to all loans without a specific allowance based on management's assessment of economic conditions, and we apply an additional amount of loss allowance to a group of loans that we have identified as having higher risk of loss.

The following table presents a rollforward of our specific and general valuation allowances for mortgage loans on real estate:



	Three Months Ended March 31, 2018						Three Months Ended March 31, 2017
	Specific Allowance			General Allowance			Specific Allowance			General Allowance
	(Dollars in thousands)
Beginning allowance balance	$	(1,418	)	$	(6,100	)	$	(1,327	)	$	(7,100	)
Charge-offs	—			—			—			—
Recoveries	722			—			—			—
Change in provision for credit losses	—			300			—			300
Ending allowance balance	$	(696	)	$	(5,800	)	$	(1,327	)	$	(6,800	)

The specific allowance represents the total credit loss allowances on loans which are individually evaluated for impairment. The general allowance is for the group of loans discussed above which are collectively evaluated for impairment. The following table presents the total outstanding principal of loans evaluated for impairment by basis of impairment method:



	March 31, 2018		December 31, 2017
	(Dollars in thousands)
Individually evaluated for impairment	$	3,186	$	5,445
Collectively evaluated for impairment	2,704,166		2,668,870
Total loans evaluated for impairment	$	2,707,352	$	2,674,315

Charge-offs include allowances that have been established on loans that were satisfied either by taking ownership of the collateral or by some other means such as discounted pay-off or loan sale. When ownership of the property is taken it is recorded at the lower of the mortgage loan's carrying value or the property's fair value (based on appraised values) less estimated costs to sell. The real estate owned is recorded as a component of Other investments and the mortgage loan is recorded as fully paid, with any allowance for credit loss that has been established charged off. Fair value of the real estate is determined by third party appraisal. Recoveries are situations where we have received a payment from the borrower in an amount greater than the carrying value of the loan (principal outstanding less specific allowance). We did not own any real estate during the three months ended March 31, 2018 and 2017.

We analyze credit risk of our mortgage loans by analyzing all available evidence on loans that are delinquent and loans that are in a workout period.



	March 31, 2018		December 31, 2017
	(Dollars in thousands)
Credit Exposure--By Payment Activity
Performing	$	2,705,957	$	2,670,657
In workout	1,395		1,436
Collateral dependent	—		2,222
	$	2,707,352	$	2,674,315

The loans that are categorized as "in workout" consist of loans that we have agreed to lower or no mortgage payments for a period of time while the borrowers address cash flow and/or operational issues. The key features of these workouts have been determined on a loan-by-loan basis. Most of these loans are in a period of low cash flow due to tenants vacating their space or tenants requesting rent relief during difficult economic periods. Generally, we have allowed the borrower a six month interest only period and in some cases a twelve month period of interest only. Interest only workout loans are expected to return to their regular debt service payments after the interest only period. Interest only loans that are not fully amortizing will have a larger balance at their balloon date than originally contracted. Fully amortizing loans that are in interest only periods will have larger debt service payments for their remaining term due to lost principal payments during the interest only period. In limited circumstances we have allowed borrowers to pay the principal portion of their loan payment into an escrow account that can be used for capital and tenant improvements for a period of not more than twelve months. In these situations new loan amortization schedules are calculated based on the principal not collected during this twelve month workout period and larger payments are collected for the remaining term of each loan. In all cases, the original interest rate and maturity date have not been modified, and we have not forgiven any principal amounts.

Mortgage loans are considered delinquent when they become 60 days or more past due. In general, when loans become 90 days past due, become collateral dependent or enter a period with no debt service payments required we place them on non-accrual status and discontinue recognizing interest income. If payments are received on a delinquent loan, interest income is recognized to the extent it would have been recognized if normal principal and interest would have been received timely. If payments are received to bring a delinquent loan back to current we will resume accruing interest income on that loan. There were no loans in non-accrual status at March 31, 2018. There were $2.2 million loans in non-accrual status at December 31, 2017.

We define collateral dependent loans as those mortgage loans for which we will depend on the value of the collateral real estate to satisfy the outstanding principal of the loan.

All of our commercial mortgage loans depend on the cash flow of the borrower to be at a sufficient level to service the principal and interest payments as they come due. In general, cash inflows of the borrowers are generated by collecting monthly rent from tenants occupying space within the borrowers' properties. Our borrowers face collateral risks such as tenants going out of business, tenants struggling to make rent payments as they become due, and tenants canceling leases and moving to other locations. We have a number of loans where the real estate is occupied by a single tenant. Our borrowers sometimes face both a reduction in cash flow on their mortgage property as well as a reduction in the fair value of the real estate collateral. If borrowers are unable to replace lost rent revenue and increases in the fair value of their property do not materialize, we could potentially incur more losses than what we have allowed for in our specific and general loan loss allowances.

Aging of financing receivables is summarized in the following table, with loans in a "workout" period as of the reporting date considered current if payments are current in accordance with agreed upon terms:



	30 - 59 Days		60 - 89 Days		90 Days and Over		Total Past Due		Current		Collateral Dependent Receivables		Total Financing Receivables
	(Dollars in thousands)
Commercial Mortgage Loans
March 31, 2018	$	—	$	—	$	—	$	—	$	2,707,352	$	—	$	2,707,352
December 31, 2017	$	—	$	—	$	—	$	—	$	2,672,093	$	2,222	$	2,674,315

Financing receivables summarized in the following two tables represent all loans that we are either not currently collecting, or those we feel it is probable we will not collect all amounts due according to the contractual terms of the loan agreements (all loans that we have worked with the borrower to alleviate short-term cash flow issues, loans delinquent for 60 days or more at the reporting date, loans we have determined to be collateral dependent and loans that we have recorded specific impairments on that we feel may continue to have performance issues).



	Recorded Investment		Unpaid Principal Balance		Related Allowance
	(Dollars in thousands)
March 31, 2018
Mortgage loans with an allowance	$	2,490	$	3,186	$	(696	)
Mortgage loans with no related allowance	1,395		1,395		—
	$	3,885	$	4,581	$	(696	)
December 31, 2017
Mortgage loans with an allowance	$	4,027	$	5,445	$	(1,418	)
Mortgage loans with no related allowance	1,436		1,436		—
	$	5,463	$	6,881	$	(1,418	)



	Average Recorded Investment		Interest Income Recognized
	(Dollars in thousands)
Three months ended March 31, 2018
Mortgage loans with an allowance	$	2,509	$	50
Mortgage loans with no related allowance	1,415		21
	$	3,924	$	71
Three months ended March 31, 2017
Mortgage loans with an allowance	$	3,291	$	72
Mortgage loans with no related allowance	1,572		23
	$	4,863	$	95

A Troubled Debt Restructuring ("TDR") is a situation where we have granted a concession to a borrower for economic or legal reasons related to the borrower's financial difficulties that we would not otherwise consider. A mortgage loan that has been granted new terms, including workout terms as described previously, would be considered a TDR if it meets conditions that would indicate a borrower is experiencing financial difficulty and the new terms constitute a concession on our part. We analyze all loans where we have agreed to workout terms and all loans that we have refinanced to determine if they meet the definition of a TDR. We consider the following factors in determining whether or not a borrower is experiencing financial difficulty:


•	borrower is in default,


•	borrower has declared bankruptcy,


•	there is growing concern about the borrower's ability to continue as a going concern,


•	borrower has insufficient cash flows to service debt,


•	borrower's inability to obtain funds from other sources, and


•	there is a breach of financial covenants by the borrower.

If the borrower is determined to be in financial difficulty, we consider the following conditions to determine if the borrower is granted a concession:


•	assets used to satisfy debt are less than our recorded investment,


•	interest rate is modified,


•	maturity date extension at an interest rate less than market rate,


•	capitalization of interest,


•	delaying principal and/or interest for a period of three months or more, and


•	partial forgiveness of the balance or charge-off.

Mortgage loan workouts, refinances or restructures that are classified as TDRs are individually evaluated and measured for impairment. A summary of mortgage loans on commercial real estate with outstanding principal at March 31, 2018 and December 31, 2017 that we determined to be TDRs are as follows:



Geographic Region	Number of TDRs	Principal Balance Outstanding		Specific Loan Loss Allowance			Net Carrying Amount
		(Dollars in thousands)
March 31, 2018
South Atlantic	1	$	2,930	$	—		$	2,930
East North Central	1	1,910		(467		)	1,443
	2	$	4,840	$	(467	)	$	4,373
December 31, 2017
South Atlantic	1	$	2,947	$	—		$	2,947
East North Central	1	1,933		(467		)	1,466
	2	$	4,880	$	(467	)	$	4,413

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Derivative Instruments

3 Months Ended

Mar. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments

None of our derivatives qualify for hedge accounting, thus, any change in the fair value of the derivatives is recognized immediately in the consolidated statements of operations. The fair value of our derivative instruments, including derivative instruments embedded in fixed index annuity contracts, presented in the consolidated balance sheets are as follows:



	March 31, 2018		December 31, 2017
	(Dollars in thousands)
Assets
Derivative instruments
Call options	$	847,741	$	1,568,380
Other assets
Interest rate caps	890		415
Interest rate swap	427		—
	$	849,058	$	1,568,795
Liabilities
Policy benefit reserves - annuity products
Fixed index annuities - embedded derivatives	$	8,233,557	$	8,790,427
Other liabilities
Interest rate swap	—		789
	$	8,233,557	$	8,791,216

The changes in fair value of derivatives included in the unaudited consolidated statements of operations are as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Change in fair value of derivatives:
Call options	$	(452,598	)	$	386,736
Interest rate swap	1,040			75
Interest rate caps	475			(278		)
	$	(451,083	)	$	386,533
Change in fair value of embedded derivatives:
Fixed index annuities—embedded derivatives	$	(1,106,023	)	$	76,210
Other changes in difference between policy benefit reserves computed using derivative accounting vs. long-duration contracts accounting	238,791			147,960
	$	(867,232	)	$	224,170

The amounts presented as "Other changes in difference between policy benefit reserves computed using derivative accounting vs. long-duration contracts accounting" represents the total change in the difference between policy benefit reserves for fixed index annuities computed under the derivative accounting standard and the long-duration contracts accounting standard at each balance sheet date, less the change in fair value of our fixed index annuities embedded derivatives that is presented as Level 3 liabilities in Note 2.

We have fixed index annuity products that guarantee the return of principal to the policyholder and credit interest based on a percentage of the gain in a specified market index. When fixed index annuity deposits are received, a portion of the deposit is used to purchase derivatives consisting of call options on the applicable market indices to fund the index credits due to fixed index annuity policyholders. Substantially all such call options are one year options purchased to match the funding requirements of the underlying policies. The call options are marked to fair value with the change in fair value included as a component of revenues. The change in fair value of derivatives includes the gains or losses recognized at the expiration of the option term or upon early termination and the changes in fair value for open positions. On the respective anniversary dates of the index policies, the index used to compute the annual index credit is reset and we purchase new one-year call options to fund the next annual index credit. We manage the cost of these purchases through the terms of our fixed index annuities, which permit us to change caps, participation rates, and/or asset fees, subject to guaranteed minimums on each policy's anniversary date. By adjusting caps, participation rates, or asset fees, we can generally manage option costs except in cases where the contractual features would prevent further modifications.

Our strategy attempts to mitigate any potential risk of loss due to the nonperformance of the counterparties to these call options through a regular monitoring process which evaluates the program's effectiveness. We do not purchase call options that would require payment or collateral to another institution and our call options do not contain counterparty credit-risk-related contingent features. We are exposed to risk of loss in the event of nonperformance by the counterparties and, accordingly, we purchase our option contracts from multiple counterparties and evaluate the creditworthiness of all counterparties prior to purchase of the contracts. All of these options have been purchased from nationally recognized financial institutions with a Standard and Poor's credit rating of A- or higher at the time of purchase and the maximum credit exposure to any single counterparty is subject to concentration limits. We also have credit support agreements that allow us to request the counterparty to provide collateral to us when the fair value of our exposure to the counterparty exceeds specified amounts.

The notional amount and fair value of our call options by counterparty and each counterparty's current credit rating are as follows:



			March 31, 2018				December 31, 2017
Counterparty	Credit Rating (S&P)	Credit Rating (Moody's)	Notional Amount		Fair Value		Notional Amount		Fair Value
			(Dollars in thousands)
Bank of America	A+	Aa3	$	5,522,691	$	91,549	$	4,645,366	$	237,955
Barclays	A	A1	3,784,024		89,471		4,135,537		154,127
BNP Paribas	A	Aa3	935,091		21,769		1,411,989		73,650
Canadian Imperial Bank of Commerce	A+	A1	4,179,179		101,280		2,808,030		84,268
Citibank, N.A.	A+	A1	4,422,448		77,256		4,104,666		219,900
Credit Suisse	A	A1	3,020,434		52,130		3,538,855		137,384
J.P. Morgan	A+	Aa3	2,118,331		85,080		1,753,649		109,689
Morgan Stanley	A+	A1	3,244,428		40,096		3,408,179		184,323
Royal Bank of Canada	AA-	A1	3,158,242		96,854		3,027,469		104,141
Societe Generale	A	A2	71,401		1,689		—		—
SunTrust	A-	Baa1	2,080,242		65,445		2,331,168		90,399
Wells Fargo	A+	Aa2	4,065,628		118,295		4,036,255		162,781
Exchange traded			260,283		6,827		296,840		9,763
			$	36,862,422	$	847,741	$	35,498,003	$	1,568,380

As of March 31, 2018 and December 31, 2017, we held $0.8 billion and $1.6 billion, respectively, of cash and cash equivalents and other securities from counterparties for derivative collateral, which is included in Other liabilities on our consolidated balance sheets. This derivative collateral limits the maximum amount of economic loss due to credit risk that we would incur if parties to the call options failed completely to perform according to the terms of the contracts to $60.2 million and $11.9 million at March 31, 2018 and December 31, 2017, respectively.

The future annual index credits on our fixed index annuities are treated as a "series of embedded derivatives" over the expected life of the applicable contract. We do not purchase call options to fund the index liabilities which may arise after the next policy anniversary date. We must value both the call options and the related forward embedded options in the policies at fair value.

We entered into an interest rate swap and interest rate caps to manage interest rate risk associated with the floating rate component on certain of our subordinated debentures. See Note 10 in our Annual Report on Form 10-K for the year ended December 31, 2017 for more information on our subordinated debentures. The terms of the interest rate swap provide that we pay a fixed rate of interest and receive a floating rate of interest. The terms of the interest rate caps limit the three month LIBOR to 2.50%. The interest rate swap and caps are not effective hedges under accounting guidance for derivative instruments and hedging activities. Therefore, we record the interest rate swap and caps at fair value and any net cash payments received or paid are included in the change in fair value of derivatives in the unaudited consolidated statements of operations.

Details regarding the interest rate swap are as follows:

Notional

Pay

March 31, 2018

December 31, 2017

Maturity Date

Amount

Receive Rate

Rate

Counterparty

Fair Value

(Dollars in thousands)

March 15, 2021

85,500

LIBOR

2.415

SunTrust

427

(789

)

Details regarding the interest rate caps are as follows:



	Notional			Cap			March 31, 2018		December 31, 2017
Maturity Date	Amount		Floating Rate	Rate		Counterparty	Fair Value		Fair Value
							(Dollars in thousands)
July 7, 2021	$	40,000	LIBOR	2.50	%	SunTrust	$	445	$	207
July 8, 2021	12,000		LIBOR	2.50	%	SunTrust	134		62
July 29, 2021	27,000		LIBOR	2.50	%	SunTrust	311		146
	$	79,000					$	890	$	415

The interest rate swap converts floating rates to fixed rates for seven years which began in March 2014. The interest rate caps cap our interest rates for seven years which began in July 2014.

Notes Payable and Amounts Due Under Repurchase Agreements

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Notes Payable and Amounts Due Under Repurchase Agreements

Notes payable includes the following:



	March 31, 2018			December 31, 2017
	(Dollars in thousands)
Senior notes due 2027
Principal	$	500,000		$	500,000
Unamortized debt issue costs	(5,457		)	(5,572		)
Unamortized discount	(328		)	(335		)
	$	494,215		$	494,093

On June 16, 2017, we issued $500 million aggregate principal amount of senior unsecured notes due 2027 which bear interest at 5.0% per year and will mature on June 15, 2027 (the "2027 Notes"). The 2027 Notes were issued at a $0.3 million discount, which is being amortized over the term of the 2027 Notes using the effective interest method. Contractual interest is payable semi-annually in arrears each June 15th and December 15th. The initial transaction fees and costs totaling $5.8 million were capitalized as deferred financing costs and are being amortized over the term of the 2027 Notes using the effective interest method.

As part of our investment strategy, we enter into securities repurchase agreements (short-term collateralized borrowings). When we do borrow cash on these repurchase agreements, we pledge collateral in the form of debt securities with fair values approximately equal to the amount due and we use the cash to purchase debt securities ahead of the time we collect the cash from selling annuity policies to avoid a lag between the investment of funds and the obligation to credit interest to policyholders. We earn investment income on the securities purchased with these borrowings at a rate in excess of the cost of these borrowings. Such borrowings averaged $7.6 million and $102.8 million and the maximum amount borrowed was $137.3 million and $274.5 million during the three months ended March 31, 2018 and March 31, 2017, respectively. The weighted average interest rate on amounts due under repurchase agreements was 1.63% and 0.64% for the three months ended March 31, 2018 and March 31, 2017, respectively.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We are occasionally involved in litigation, both as a defendant and as a plaintiff. In addition, state regulatory bodies, such as state insurance departments, the Securities and Exchange Commission ("SEC"), Financial Industry Regulatory Authority, the Department of Labor ("DOL"), and other regulatory bodies regularly make inquiries and conduct examinations or investigations concerning our compliance with, among other things, insurance laws, securities laws, the Employee Retirement Income Security Act of 1974, as amended, and laws governing the activities of broker/dealers. In accordance with applicable accounting guidelines, we establish an accrued liability for litigation and regulatory matters when those matters present loss contingencies that are both probable and estimable. As a litigation or regulatory matter is developing we, in conjunction with outside counsel, evaluate on an ongoing basis whether the matter presents a loss contingency that meets conditions indicating the need for accrual and/or disclosure, and if not the matter will continue to be monitored for further developments. If and when the loss contingency related to litigation or regulatory matters is deemed to be both probable and estimable, we will establish an accrued liability with respect to that matter and will continue to monitor the matter for further developments that may affect the amount of the accrued liability. There can be no assurance that any pending or future litigation will not have a material adverse effect on our business, financial condition, or results of operations. In addition to our commitments to fund mortgage loans, we have unfunded commitments at March 31, 2018 to limited partnerships of $48.4 million and to secured bank loans of $6.2 million.

Earnings Per Share

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Earnings Per Share

The following table sets forth the computation of earnings per common share and earnings per common share - assuming dilution:



	Three Months Ended March 31,
	2018		2017
	(Dollars in thousands, except per share data)
Numerator:
Net income - numerator for earnings per common share	$	140,962	$	53,939

Denominator:
Weighted average common shares outstanding	90,017,166		88,647,078
Effect of dilutive securities:
Stock options and deferred compensation agreements	850,292		948,317
Restricted stock and restricted stock units	271,890		380,217
Denominator for earnings per common share - assuming dilution	91,139,348		89,975,612

Earnings per common share	$	1.57	$	0.61
Earnings per common share - assuming dilution	$	1.55	$	0.60

There were no options to purchase shares of our common stock outstanding excluded from the computation of diluted earnings per share during the three months ended March 31, 2018 or 2017, as the exercise price of all options outstanding was less than the average market price of our common shares for those periods.

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2018

Accounting Policies [Abstract]

Adopted and New Accounting Pronouncements, Policy

Adopted Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board ("FASB") issued an accounting standards update ("ASU") related to revenue arising from contracts with customers. This ASU, which replaces most current revenue recognition guidance, including industry specific guidance, prescribes that an entity should recognize revenue to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We adopted this ASU on January 1, 2018. The adoption of this ASU had no impact on our consolidated financial statements as revenues related to insurance contracts and investment contracts are excluded from its scope.

In January 2016, the FASB issued an ASU that, among other aspects of recognition, measurement, presentation and disclosure of financial instruments, primarily requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. However, an entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Additionally, it changes the accounting for financial liabilities measured at fair value under the fair value option and eliminates some disclosures regarding fair value of financial assets and liabilities measured at amortized cost. We adopted this ASU on January 1, 2018. The adoption of this ASU had no impact on our consolidated financial statements.

In August 2016, the FASB issued an ASU that clarifies how certain cash receipts and cash payments are to be presented and classified in the statement of cash flows. We adopted this ASU on January 1, 2018. The adoption of this ASU resulted in a reclassification of certain cash flows related to equity method investment distributions from investing activities to operating activities within our consolidated statements of cash flows.

In February 2018, the FASB issued an ASU that allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 ("Tax Reform"). We adopted this ASU on January 1, 2018. The adoption of this ASU resulted in a reclassification of $128 million between accumulated other comprehensive income and retained earnings within our consolidated balance sheet.

New Accounting Pronouncements

In February 2016, the FASB issued an ASU that will require recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This ASU affects accounting and disclosure more dramatically for lessees as accounting for lessors is mainly unchanged. This ASU will be effective for us on January 1, 2019, with early adoption permitted. We are in the process of evaluating the impact this guidance may have on our consolidated financial statements.

In June 2016, the FASB issued an ASU that significantly changes the impairment model for most financial assets that are measured at amortized cost and certain other instruments from an incurred loss model to an expected loss model that requires these assets be presented at the net amount expected to be collected. In addition, credit losses on available for sale debt securities should be recorded through an allowance account. This ASU will be effective for us on January 1, 2020, with early adoption permitted. While we are still in the process of evaluating the impact this guidance will have on our consolidated financial statements, we believe the new impairment model will lead to earlier recognition of credit losses for our commercial mortgage loans.

In March 2017, the FASB issued an ASU that applies to certain callable debt securities where the amortized cost basis is at a premium to the price repayable by the issuer at the earliest call date. Under this guidance, the premium will be amortized to the first call date. This ASU will be effective for us on January 1, 2019, with early adoption permitted. We are in the process of evaluating the impact this guidance may have on our consolidated financial statements.

Income Tax Reform

As a result of Tax Reform, the federal corporate tax rate was reduced from 35% to 21% effective January 1, 2018.

Fair Values of Financial Instruments, Policy


Level 1—	Quoted prices are available in active markets for identical financial instruments as of the reporting date. We do not adjust the quoted price for these financial instruments, even in situations where we hold a large position and a sale could reasonably impact the quoted price.


Level 2—	Quoted prices in active markets for similar financial instruments, quoted prices for identical or similar financial instruments in markets that are not active; and models and other valuation methodologies using inputs other than quoted prices that are observable.

Level 3—

Transfers of securities among the levels occur at times and depend on the type of inputs used to determine fair value of each security.

Investments, Policy


•	the length of time and the extent to which the fair value has been less than amortized cost or cost;


•	whether the issuer is current on all payments and all contractual payments have been made as agreed;


•	the remaining payment terms and the financial condition and near-term prospects of the issuer;


•	the lack of ability to refinance due to liquidity problems in the credit market;


•	the fair value of any underlying collateral;


•	the existence of any credit protection available;


•	our intent to sell and whether it is more likely than not we would be required to sell prior to recovery for debt securities;


•	consideration of rating agency actions; and


•	changes in estimated cash flows of mortgage and asset backed securities.

Mortgage Loans on Real Estate, Allowance for Loan Losses, Policy

Mortgage Loans on Real Estate, Real Estate Acquired Through Foreclosure, Policy

Mortgage Loans on Real Estate, Non-Accrual Loan Status, Policy

Mortgage Loans on Real Estate, Troubled Debt Restructuring, Policy


•	borrower is in default,


•	borrower has declared bankruptcy,


•	there is growing concern about the borrower's ability to continue as a going concern,


•	borrower has insufficient cash flows to service debt,


•	borrower's inability to obtain funds from other sources, and


•	there is a breach of financial covenants by the borrower.

If the borrower is determined to be in financial difficulty, we consider the following conditions to determine if the borrower is granted a concession:


•	assets used to satisfy debt are less than our recorded investment,


•	interest rate is modified,


•	maturity date extension at an interest rate less than market rate,


•	capitalization of interest,


•	delaying principal and/or interest for a period of three months or more, and


•	partial forgiveness of the balance or charge-off.

Mortgage loan workouts, refinances or restructures that are classified as TDRs are individually evaluated and measured for impairment.

Commitments and Contingencies, Policy

In accordance with applicable accounting guidelines, we establish an accrued liability for litigation and regulatory matters when those matters present loss contingencies that are both probable and estimable. As a litigation or regulatory matter is developing we, in conjunction with outside counsel, evaluate on an ongoing basis whether the matter presents a loss contingency that meets conditions indicating the need for accrual and/or disclosure, and if not the matter will continue to be monitored for further developments. If and when the loss contingency related to litigation or regulatory matters is deemed to be both probable and estimable, we will establish an accrued liability with respect to that matter and will continue to monitor the matter for further developments that may affect the amount of the accrued liability.

- Definition

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.

+ References + Details

Fair Values of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Carrying Amounts and Fair Values of Financial Instruments

The following sets forth a comparison of the carrying amounts and fair values of our financial instruments:



	March 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(Dollars in thousands)
Assets
Fixed maturity securities:
Available for sale	$	45,551,348	$	45,551,348	$	45,372,989	$	45,372,989
Held for investment	77,043		69,441		77,041		76,460
Mortgage loans on real estate	2,699,637		2,684,976		2,665,531		2,670,037
Derivative instruments	847,741		847,741		1,568,380		1,568,380
Other investments	481,825		472,642		616,764		605,894
Cash and cash equivalents	723,784		723,784		1,434,045		1,434,045
Coinsurance deposits	4,871,912		4,402,849		4,858,289		4,347,990
Interest rate caps	890		890		415		415
Interest rate swap	427		427		—		—
Counterparty collateral	124,778		124,778		186,108		186,108

Liabilities
Policy benefit reserves	55,713,429		47,137,678		55,786,011		46,344,931
Single premium immediate annuity (SPIA) benefit reserves	279,678		288,991		282,563		292,153
Notes payable	494,215		506,345		494,093		521,800
Subordinated debentures	242,667		229,588		242,565		244,117
Amounts due under repurchase agreements	137,223		137,223		—		—
Interest rate swap	—		—		789		789

Assets and Liabilities Measured at Fair Value on a Recurring Basis, By Fair Value Hierarchy Level

Our assets and liabilities which are measured at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 are presented below based on the fair value hierarchy levels:



	Total Fair Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	(Dollars in thousands)
March 31, 2018
Assets
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,433	$	5,541	$	5,892	$	—
United States Government sponsored agencies	1,270,106		—		1,270,106		—
United States municipalities, states and territories	4,137,005		—		4,137,005		—
Foreign government obligations	231,671		—		231,671		—
Corporate securities	29,584,128		375		29,583,753		—
Residential mortgage backed securities	1,102,609		—		1,102,609		—
Commercial mortgage backed securities	5,596,882		—		5,596,882		—
Other asset backed securities	3,617,514		—		3,617,514		—
Other investments: equity securities	157,431		150,000		7,431		—
Derivative instruments	847,741		—		847,741		—
Cash and cash equivalents	723,784		723,784		—		—
Interest rate caps	890		—		890		—
Interest rate swap	427		—		427		—
Counterparty collateral	124,778		—		124,778		—
	$	47,406,399	$	879,700	$	46,526,699	$	—
Liabilities
Fixed index annuities - embedded derivatives	$	8,233,557	$	—	$	—	$	8,233,557
	$	8,233,557	$	—	$	—	$	8,233,557

December 31, 2017
Assets
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,876	$	5,640	$	6,236	$	—
United States Government sponsored agencies	1,305,017		—		1,305,017		—
United States municipalities, states and territories	4,166,812		—		4,166,812		—
Foreign government obligations	239,360		—		239,360		—
Corporate securities	29,878,971		5		29,878,966		—
Residential mortgage backed securities	1,105,567		—		1,105,567		—
Commercial mortgage backed securities	5,544,850		—		5,544,850		—
Other asset backed securities	3,120,536		—		3,120,536		—
Other investments: equity securities, available for sale	292,429		285,000		7,429		—
Derivative instruments	1,568,380		—		1,568,380		—
Cash and cash equivalents	1,434,045		1,434,045		—		—
Interest rate caps	415		—		415		—
Counterparty collateral	186,108		—		186,108		—
	$	48,854,366	$	1,724,690	$	47,129,676	$	—
Liabilities
Interest rate swap	$	789	$	—	$	789	$	—
Fixed index annuities - embedded derivatives	8,790,427		—		—		8,790,427
	$	8,791,216	$	—	$	789	$	8,790,427

Schedule of Assumptions Used in Estimating Fair Value

The following table presents average lapse rate and partial withdrawal rate assumptions, by contract duration, used in estimating the fair value of the embedded derivative component of our fixed index annuity policy benefit reserves at each reporting date:



	Average Lapse Rates		Average Partial Withdrawal Rates
Contract Duration (Years)	March 31, 2018	December 31, 2017	March 31, 2018	December 31, 2017
1 - 5	2.11%	1.83%	3.33%	3.32%
6 - 10	7.30%	7.01%	3.33%	3.32%
11 - 15	11.33%	11.31%	3.34%	3.34%
16 - 20	11.91%	11.96%	3.24%	3.20%
20+	11.58%	11.62%	3.21%	3.20%

Liabilities Measured at Fair Value on Recurring Basis, Level 3 Reconciliation



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Fixed index annuities - embedded derivatives
Beginning balance	$	8,790,427		$	6,563,288
Premiums less benefits	549,153			411,502
Change in fair value, net	(1,106,023		)	76,210
Ending balance	$	8,233,557		$	7,051,000

Investments (Tables)

3 Months Ended

Mar. 31, 2018

Investments [Abstract]

Schedule of Fixed Maturity Securities

At March 31, 2018 and December 31, 2017, the amortized cost and fair value of fixed maturity securities were as follows:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
March 31, 2018
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,696	$	110	$	(373	)	$	11,433
United States Government sponsored agencies	1,308,312		21,134		(59,340		)	1,270,106
United States municipalities, states and territories	3,853,098		296,762		(12,855		)	4,137,005
Foreign government obligations	227,617		8,502		(4,448		)	231,671
Corporate securities	28,801,351		1,186,607		(403,830		)	29,584,128
Residential mortgage backed securities	1,044,032		65,581		(7,004		)	1,102,609
Commercial mortgage backed securities	5,685,290		33,098		(121,506		)	5,596,882
Other asset backed securities	3,579,417		52,730		(14,633		)	3,617,514
	$	44,510,813	$	1,664,524	$	(623,989	)	$	45,551,348
Held for investment:
Corporate security	$	77,043	$	—	$	(7,602	)	$	69,441

December 31, 2017
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	11,861	$	162	$	(147	)	$	11,876
United States Government sponsored agencies	1,308,290		28,457		(31,730		)	1,305,017
United States municipalities, states and territories	3,804,360		366,048		(3,596		)	4,166,812
Foreign government obligations	228,214		13,171		(2,025		)	239,360
Corporate securities	28,127,653		1,897,005		(145,687		)	29,878,971
Residential mortgage backed securities	1,028,484		79,554		(2,471		)	1,105,567
Commercial mortgage backed securities	5,531,922		82,768		(69,840		)	5,544,850
Other asset backed securities	3,075,975		57,966		(13,405		)	3,120,536
	$	43,116,759	$	2,525,131	$	(268,901	)	$	45,372,989
Held for investment:
Corporate security	$	77,041	$	—	$	(581	)	$	76,460

Other investments: equity securities, available for sale:
Finance, insurance, and real estate	$	292,429	$	—	$	—		$	292,429

Schedule of Fixed Maturity Securities by Contractual Maturity Date



	Available for sale				Held for investment
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	218,825	$	223,487	$	—	$	—
Due after one year through five years	5,615,360		5,673,765		—		—
Due after five years through ten years	10,439,109		10,428,466		—		—
Due after ten years through twenty years	9,188,746		9,774,966		—		—
Due after twenty years	8,740,034		9,133,659		77,043		69,441
	34,202,074		35,234,343		77,043		69,441
Residential mortgage backed securities	1,044,032		1,102,609		—		—
Commercial mortgage backed securities	5,685,290		5,596,882		—		—
Other asset backed securities	3,579,417		3,617,514		—		—
	$	44,510,813	$	45,551,348	$	77,043	$	69,441

Schedule of Components of Net Unrealized Gains on Available for Sale Fixed Maturity Securities Reported as Separate Component of Stockholders' Equity

Net unrealized gains on available for sale fixed maturity securities reported as a separate component of stockholders' equity were comprised of the following:



	March 31, 2018			December 31, 2017
	(Dollars in thousands)
Net unrealized gains on available for sale fixed maturity securities	$	1,040,535		$	2,256,230
Adjustments for assumed changes in amortization of deferred policy acquisition costs and deferred sales inducements	(562,755		)	(1,206,078		)
Deferred income tax valuation allowance reversal	22,534			22,534
Deferred income tax expense (a)	(100,332		)	(348,087		)
Net unrealized gains reported as accumulated other comprehensive income	$	399,982		$	724,599


(a)	December 31, 2017 includes $128 million related to the impact of Tax Reform that was reclassified between accumulated other comprehensive income and retained earnings within our consolidated balance sheet during the first quarter of 2018. For more information regarding the reclassification, see Note 1 to our unaudited consolidated financial statements.

Schedule of Credit Quality of Fixed Maturity Security Portfolio by NAIC Designation

The following table summarizes the credit quality, as determined by NAIC designation, of our fixed maturity portfolio as of the dates indicated:



	March 31, 2018				December 31, 2017
NAIC Designation	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
1	$	27,142,276	$	27,984,297	$	26,669,427	$	28,274,379
2	15,897,296		16,147,267		15,198,551		15,869,219
3	1,350,395		1,316,146		1,161,737		1,157,420
4	170,754		145,085		134,838		117,542
5	17,108		19,926		17,015		20,927
6	10,027		8,068		12,232		9,962
	$	44,587,856	$	45,620,789	$	43,193,800	$	45,449,449

Schedule of Gross Unrealized Losses on Investments, By Category and Length of Time



	Less than 12 months					12 months or more					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(Dollars in thousands)
March 31, 2018
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	3,193	$	(50	)	$	6,380	$	(323	)	$	9,573	$	(373	)
United States Government sponsored agencies	74,632		(1,513		)	932,691		(57,827		)	1,007,323		(59,340		)
United States municipalities, states and territories	224,928		(5,000		)	124,097		(7,855		)	349,025		(12,855		)
Foreign government obligations	127,620		(2,442		)	12,297		(2,006		)	139,917		(4,448		)
Corporate securities:
Finance, insurance and real estate	1,980,979		(46,008		)	599,683		(48,915		)	2,580,662		(94,923		)
Manufacturing, construction and mining	1,378,585		(29,518		)	229,805		(17,840		)	1,608,390		(47,358		)
Utilities and related sectors	1,830,012		(41,549		)	239,209		(18,121		)	2,069,221		(59,670		)
Wholesale/retail trade	755,307		(16,446		)	173,229		(16,809		)	928,536		(33,255		)
Services, media and other	3,498,221		(85,932		)	855,680		(82,692		)	4,353,901		(168,624		)
Residential mortgage backed securities	286,561		(4,535		)	24,870		(2,469		)	311,431		(7,004		)
Commercial mortgage backed securities	2,495,283		(43,167		)	1,310,142		(78,339		)	3,805,425		(121,506		)
Other asset backed securities	797,174		(6,376		)	187,857		(8,257		)	985,031		(14,633		)
	$	13,452,495	$	(282,536	)	$	4,695,940	$	(341,453	)	$	18,148,435	$	(623,989	)
Held for investment:
Corporate security:
Insurance	$	—	$	—		$	69,441	$	(7,602	)	$	69,441	$	(7,602	)

December 31, 2017
Fixed maturity securities:
Available for sale:
United States Government full faith and credit	$	1,565	$	(10	)	$	6,731	$	(137	)	$	8,296	$	(147	)
United States Government sponsored agencies	44,794		(180		)	958,965		(31,550		)	1,003,759		(31,730		)
United States municipalities, states and territories	44,736		(128		)	128,499		(3,468		)	173,235		(3,596		)
Foreign government obligations	49,663		(337		)	12,625		(1,688		)	62,288		(2,025		)
Corporate securities:
Finance, insurance and real estate	456,244		(5,135		)	600,655		(28,043		)	1,056,899		(33,178		)
Manufacturing, construction and mining	222,985		(3,475		)	231,196		(10,849		)	454,181		(14,324		)
Utilities and related sectors	395,183		(4,099		)	249,416		(8,901		)	644,599		(13,000		)
Wholesale/retail trade	152,941		(1,249		)	178,635		(11,371		)	331,576		(12,620		)
Services, media and other	729,124		(19,000		)	891,654		(53,565		)	1,620,778		(72,565		)
Residential mortgage backed securities	39,771		(387		)	32,917		(2,084		)	72,688		(2,471		)
Commercial mortgage backed securities	1,096,757		(10,385		)	1,306,437		(59,455		)	2,403,194		(69,840		)
Other asset backed securities	765,531		(3,499		)	217,595		(9,906		)	983,126		(13,405		)
	$	3,999,294	$	(47,884	)	$	4,815,325	$	(221,017	)	$	8,814,619	$	(268,901	)
Held for investment:
Corporate security:
Insurance	$	—	$	—		$	76,460	$	(581	)	$	76,460	$	(581	)

Schedule of Changes in Net Unrealized Gains/Losses on Investments

Changes in net unrealized gains on investments for the three months ended March 31, 2018 and 2017 are as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Fixed maturity securities held for investment carried at amortized cost	$	(7,021	)	$	(1,976	)
Investments carried at fair value:
Fixed maturity securities, available for sale	$	(1,215,695	)	$	281,094
Equity securities, available for sale	—			(13		)
	(1,215,695		)	281,081
Adjustment for effect on other balance sheet accounts:
Deferred policy acquisition costs and deferred sales inducements	643,323			(150,962		)
Deferred income tax asset/liability	120,201			(45,542		)
	763,524			(196,504		)
Change in net unrealized gains on investments carried at fair value	$	(452,171	)	$	84,577

Net Realized Gains (Losses) on Investments

Net realized gains on investments, excluding net OTTI losses for the three months ended March 31, 2018 and 2017, are as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Available for sale fixed maturity securities:
Gross realized gains	$	1,382		$	5,572
Gross realized losses	(2,102		)	(3,563		)
	(720		)	2,009

Other investments:
Gain on sale of real estate	—			29

Mortgage loans on real estate:
Decrease in allowance for credit losses	300			300
Recovery of specific allowance	722			—
	1,022			300
	$	302		$	2,338

Significant Assumptions Used to Determine the Credit Loss Component of Other Than Temporary Impairment on Residential Mortgage Backed Securities



		Discount Rate				Default Rate				Loss Severity
Sector	Vintage	Min		Max		Min		Max		Min		Max
Three months ended March 31, 2017
Prime	2005	7.7	%	7.7	%	8	%	8	%	50	%	50	%
	2007	6.2	%	6.3	%	15	%	18	%	50	%	60	%

Other Than Temporary Impairment by Asset Type

The following table summarizes other than temporary impairments for the three months ended March 31, 2018 and 2017, by asset type:



	Number of Securities	Total OTTI Losses			Portion of OTTI Losses Recognized in (from) Other Comprehensive Income			Net OTTI Losses Recognized in Operations
		(Dollars in thousands)
Three months ended March 31, 2018
Fixed maturity securities, available for sale:
Corporate securities:
Consumer discretionary	1	$	(907	)	$	—		$	(907	)

Three months ended March 31, 2017
Fixed maturity securities, available for sale:
Residential mortgage backed securities	3	$	—		$	(141	)	$	(141	)

Other Than Temporary Impairment, Credit Losses Recognized in Earnings

The cumulative portion of other than temporary impairments determined to be credit losses which have been recognized in operations for debt securities are summarized as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Cumulative credit loss at beginning of period	$	(157,066	)	$	(166,375	)
Credit losses on securities for which OTTI has not previously been recognized	(907		)	—
Additional credit losses on securities for which OTTI has previously been recognized	—			(141		)
Accumulated losses on securities that were disposed of during the period	3,900			13,939
Cumulative credit loss at end of period	$	(154,073	)	$	(152,577	)

Schedule of Other Than Temporary Impairment Losses, Investments



	Amortized Cost		OTTI Recognized in Other Comprehensive Income			Change in Fair Value Since OTTI was Recognized			Fair Value
	(Dollars in thousands)
March 31, 2018
Fixed maturity securities, available for sale:
Corporate securities	$	17,947	$	(3,700	)	$	10,012		$	24,259
Residential mortgage backed securities	282,835		(168,355		)	198,719			313,199
Other asset backed securities	4,567		(1,356		)	(1,631		)	1,580
	$	305,349	$	(173,411	)	$	207,100		$	339,038
December 31, 2017
Fixed maturity securities, available for sale:
Corporate securities	$	13,015	$	(4,263	)	$	10,739		$	19,491
Residential mortgage backed securities	297,582		(168,355		)	201,620			330,847
Other asset backed securities	4,567		(1,356		)	(1,875		)	1,336
	$	315,164	$	(173,974	)	$	210,484		$	351,674

Mortgage Loans on Real Estate (Tables)

3 Months Ended

Mar. 31, 2018

Mortgage Loans on Real Estate [Abstract]

Summary of Mortgage Loan Portfolio

Our mortgage loan portfolio is summarized in the following table. There were commitments outstanding of $51.7 million at March 31, 2018.



	March 31, 2018			December 31, 2017
	(Dollars in thousands)
Principal outstanding	$	2,707,352		$	2,674,315
Loan loss allowance	(6,496		)	(7,518		)
Deferred prepayment fees	(1,219		)	(1,266		)
Carrying value	$	2,699,637		$	2,665,531

Mortgage Loan Portfolio Summarized by Geographic Region and Property Type

The mortgage loan portfolio is summarized by geographic region and property type as follows:



	March 31, 2018				December 31, 2017
	Principal		Percent		Principal		Percent
	(Dollars in thousands)
Geographic distribution
East	$	563,593	20.8	%	$	548,067	20.5	%
Middle Atlantic	166,782		6.2	%	163,485		6.1	%
Mountain	317,872		11.7	%	308,486		11.5	%
New England	12,146		0.5	%	12,265		0.5	%
Pacific	482,593		17.8	%	466,030		17.4	%
South Atlantic	613,999		22.7	%	609,736		22.8	%
West North Central	315,339		11.6	%	324,808		12.2	%
West South Central	235,028		8.7	%	241,438		9.0	%
	$	2,707,352	100.0	%	$	2,674,315	100.0	%
Property type distribution
Office	$	270,066	10.0	%	$	283,926	10.6	%
Medical Office	32,902		1.2	%	34,338		1.3	%
Retail	1,051,749		38.8	%	1,040,028		38.9	%
Industrial/Warehouse	703,892		26.0	%	677,770		25.3	%
Apartment	471,097		17.4	%	462,897		17.3	%
Mixed use/other	177,646		6.6	%	175,356		6.6	%
	$	2,707,352	100.0	%	$	2,674,315	100.0	%

Rollforward of Allowance for Credit Losses

The following table presents a rollforward of our specific and general valuation allowances for mortgage loans on real estate:



	Three Months Ended March 31, 2018						Three Months Ended March 31, 2017
	Specific Allowance			General Allowance			Specific Allowance			General Allowance
	(Dollars in thousands)
Beginning allowance balance	$	(1,418	)	$	(6,100	)	$	(1,327	)	$	(7,100	)
Charge-offs	—			—			—			—
Recoveries	722			—			—			—
Change in provision for credit losses	—			300			—			300
Ending allowance balance	$	(696	)	$	(5,800	)	$	(1,327	)	$	(6,800	)

Impaired Mortgage Loans on Real Estate by Basis of Impairment

The following table presents the total outstanding principal of loans evaluated for impairment by basis of impairment method:



	March 31, 2018		December 31, 2017
	(Dollars in thousands)
Individually evaluated for impairment	$	3,186	$	5,445
Collectively evaluated for impairment	2,704,166		2,668,870
Total loans evaluated for impairment	$	2,707,352	$	2,674,315

Mortgage Loans By Credit Quality Indicator

We analyze credit risk of our mortgage loans by analyzing all available evidence on loans that are delinquent and loans that are in a workout period.



	March 31, 2018		December 31, 2017
	(Dollars in thousands)
Credit Exposure--By Payment Activity
Performing	$	2,705,957	$	2,670,657
In workout	1,395		1,436
Collateral dependent	—		2,222
	$	2,707,352	$	2,674,315

Aging of Financing Receivables



	30 - 59 Days		60 - 89 Days		90 Days and Over		Total Past Due		Current		Collateral Dependent Receivables		Total Financing Receivables
	(Dollars in thousands)
Commercial Mortgage Loans
March 31, 2018	$	—	$	—	$	—	$	—	$	2,707,352	$	—	$	2,707,352
December 31, 2017	$	—	$	—	$	—	$	—	$	2,672,093	$	2,222	$	2,674,315

Impaired Financing Receivables



	Recorded Investment		Unpaid Principal Balance		Related Allowance
	(Dollars in thousands)
March 31, 2018
Mortgage loans with an allowance	$	2,490	$	3,186	$	(696	)
Mortgage loans with no related allowance	1,395		1,395		—
	$	3,885	$	4,581	$	(696	)
December 31, 2017
Mortgage loans with an allowance	$	4,027	$	5,445	$	(1,418	)
Mortgage loans with no related allowance	1,436		1,436		—
	$	5,463	$	6,881	$	(1,418	)



	Average Recorded Investment		Interest Income Recognized
	(Dollars in thousands)
Three months ended March 31, 2018
Mortgage loans with an allowance	$	2,509	$	50
Mortgage loans with no related allowance	1,415		21
	$	3,924	$	71
Three months ended March 31, 2017
Mortgage loans with an allowance	$	3,291	$	72
Mortgage loans with no related allowance	1,572		23
	$	4,863	$	95

Troubled Debt Restructurings on Financing Receivables

A summary of mortgage loans on commercial real estate with outstanding principal at March 31, 2018 and December 31, 2017 that we determined to be TDRs are as follows:



Geographic Region	Number of TDRs	Principal Balance Outstanding		Specific Loan Loss Allowance			Net Carrying Amount
		(Dollars in thousands)
March 31, 2018
South Atlantic	1	$	2,930	$	—		$	2,930
East North Central	1	1,910		(467		)	1,443
	2	$	4,840	$	(467	)	$	4,373
December 31, 2017
South Atlantic	1	$	2,947	$	—		$	2,947
East North Central	1	1,933		(467		)	1,466
	2	$	4,880	$	(467	)	$	4,413

Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Fair Value of Derivative Instruments as Presented in the Consolidated Balance Sheets

The fair value of our derivative instruments, including derivative instruments embedded in fixed index annuity contracts, presented in the consolidated balance sheets are as follows:



	March 31, 2018		December 31, 2017
	(Dollars in thousands)
Assets
Derivative instruments
Call options	$	847,741	$	1,568,380
Other assets
Interest rate caps	890		415
Interest rate swap	427		—
	$	849,058	$	1,568,795
Liabilities
Policy benefit reserves - annuity products
Fixed index annuities - embedded derivatives	$	8,233,557	$	8,790,427
Other liabilities
Interest rate swap	—		789
	$	8,233,557	$	8,791,216

Schedule of Changes in Fair Value of Derivative Instruments

The changes in fair value of derivatives included in the unaudited consolidated statements of operations are as follows:



	Three Months Ended March 31,
	2018			2017
	(Dollars in thousands)
Change in fair value of derivatives:
Call options	$	(452,598	)	$	386,736
Interest rate swap	1,040			75
Interest rate caps	475			(278		)
	$	(451,083	)	$	386,533
Change in fair value of embedded derivatives:
Fixed index annuities—embedded derivatives	$	(1,106,023	)	$	76,210
Other changes in difference between policy benefit reserves computed using derivative accounting vs. long-duration contracts accounting	238,791			147,960
	$	(867,232	)	$	224,170

Schedule of Call Options by Counterparty

The notional amount and fair value of our call options by counterparty and each counterparty's current credit rating are as follows:



			March 31, 2018				December 31, 2017
Counterparty	Credit Rating (S&P)	Credit Rating (Moody's)	Notional Amount		Fair Value		Notional Amount		Fair Value
			(Dollars in thousands)
Bank of America	A+	Aa3	$	5,522,691	$	91,549	$	4,645,366	$	237,955
Barclays	A	A1	3,784,024		89,471		4,135,537		154,127
BNP Paribas	A	Aa3	935,091		21,769		1,411,989		73,650
Canadian Imperial Bank of Commerce	A+	A1	4,179,179		101,280		2,808,030		84,268
Citibank, N.A.	A+	A1	4,422,448		77,256		4,104,666		219,900
Credit Suisse	A	A1	3,020,434		52,130		3,538,855		137,384
J.P. Morgan	A+	Aa3	2,118,331		85,080		1,753,649		109,689
Morgan Stanley	A+	A1	3,244,428		40,096		3,408,179		184,323
Royal Bank of Canada	AA-	A1	3,158,242		96,854		3,027,469		104,141
Societe Generale	A	A2	71,401		1,689		—		—
SunTrust	A-	Baa1	2,080,242		65,445		2,331,168		90,399
Wells Fargo	A+	Aa2	4,065,628		118,295		4,036,255		162,781
Exchange traded			260,283		6,827		296,840		9,763
			$	36,862,422	$	847,741	$	35,498,003	$	1,568,380

Schedule of Interest Rate Derivatives

Details regarding the interest rate swap are as follows:

Notional

Pay

March 31, 2018

December 31, 2017

Maturity Date

Amount

Receive Rate

Rate

Counterparty

Fair Value

(Dollars in thousands)

March 15, 2021

85,500

LIBOR

2.415

SunTrust

427

(789

)

Details regarding the interest rate caps are as follows:



	Notional			Cap			March 31, 2018		December 31, 2017
Maturity Date	Amount		Floating Rate	Rate		Counterparty	Fair Value		Fair Value
							(Dollars in thousands)
July 7, 2021	$	40,000	LIBOR	2.50	%	SunTrust	$	445	$	207
July 8, 2021	12,000		LIBOR	2.50	%	SunTrust	134		62
July 29, 2021	27,000		LIBOR	2.50	%	SunTrust	311		146
	$	79,000					$	890	$	415

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

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+ Details

Notes Payable and Amounts Due Under Repurchase Agreements (Tables)

3 Months Ended

Mar. 31, 2018

Debt Disclosure [Abstract]

Schedule of Notes Payable

Notes payable includes the following:



	March 31, 2018			December 31, 2017
	(Dollars in thousands)
Senior notes due 2027
Principal	$	500,000		$	500,000
Unamortized debt issue costs	(5,457		)	(5,572		)
Unamortized discount	(328		)	(335		)
	$	494,215		$	494,093

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 1
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+ Details

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table sets forth the computation of earnings per common share and earnings per common share - assuming dilution:



	Three Months Ended March 31,
	2018		2017
	(Dollars in thousands, except per share data)
Numerator:
Net income - numerator for earnings per common share	$	140,962	$	53,939

Denominator:
Weighted average common shares outstanding	90,017,166		88,647,078
Effect of dilutive securities:
Stock options and deferred compensation agreements	850,292		948,317
Restricted stock and restricted stock units	271,890		380,217
Denominator for earnings per common share - assuming dilution	91,139,348		89,975,612

Earnings per common share	$	1.57	$	0.61
Earnings per common share - assuming dilution	$	1.55	$	0.60

Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Federal corporate tax rate, percent	21.00%	35.00%
Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement, effect of adoption, quantification	$ 128	$ 128

Fair Values of Financial Instruments (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) Basis_Points	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Level 1 to Level 2 transfers, amount	$ 0		$ 0
Liabilities, Level 1 to Level 2 transfers, amount	0		0
Assets, Level 2 to Level 1 transfers, amount	0		0
Liabilities, Level 2 to Level 1 transfers, amount	0		0
Assets, transfers into Level 3, amount	0	$ 0
Liabilities, transfers into Level 3, amount	0	0
Assets, transfers out of Level 3, amount	0	0
Liabilities, transfers out of Level 3, amount	0	$ 0
Coinsurance ceded, fixed index annuities embedded derivatives	$ 4,871,912		4,858,289
Fair Value, Sensitivity, Increase in Discount Rate by 10 Percent [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, sensitivity, discount rate adjustment (basis points) \| Basis_Points	100
Fixed index annuities embedded derivative, adjustment due to change in discount rate	$ (529,000)
Deferred policy scquisition costs and deferred sales inducements, combined balance, adjustment due to change in discount rate	$ (321,000)
Fair Value, Sensitivity, Decrease in Discount Rate by 10 Percent [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, sensitivity, discount rate adjustment (basis points) \| Basis_Points	100
Fixed index annuities embedded derivative, adjustment due to change in discount rate	$ 588,500
Deferred policy scquisition costs and deferred sales inducements, combined balance, adjustment due to change in discount rate	340,900
Fixed Index Annuities - Embedded Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Coinsurance ceded, fixed index annuities embedded derivatives	$ 529,600		$ 539,700

Fair Values of Financial Instruments (Fair Values and Carrying Amounts of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Held for investment	$ 69,441	$ 76,460
Other investments	481,825	616,764
Coinsurance deposits	4,871,912	4,858,289
Liabilities
Policy benefit reserves	56,072,140	56,142,673
Interest Rate Caps [Member]
Assets
Derivative instruments	890	415
Carrying Amount [Member]
Assets
Available for sale securities	45,551,348	45,372,989
Held for investment	77,043	77,041
Mortgage loans on real estate	2,699,637	2,665,531
Derivative instruments	847,741	1,568,380
Other investments	481,825	616,764
Cash and cash equivalents	723,784	1,434,045
Coinsurance deposits	4,871,912	4,858,289
Counterparty collateral	124,778	186,108
Liabilities
Policy benefit reserves	55,713,429	55,786,011
Single premium immediate annuity (SPIA) benefit reserves	279,678	282,563
Notes payable	494,215	494,093
Subordinated debentures	242,667	242,565
Amounts due under repurchase agreements	137,223	0
Carrying Amount [Member] \| Interest Rate Caps [Member]
Assets
Interest rate derivative assets	890	415
Carrying Amount [Member] \| Interest Rate Swap [Member]
Assets
Interest rate derivative assets	427	0
Liabilities
Interest rate derivative liabilities	0	789
Fair Value [Member]
Assets
Available for sale securities	45,551,348	45,372,989
Held for investment	69,441	76,460
Mortgage loans on real estate	2,684,976	2,670,037
Derivative instruments	847,741	1,568,380
Other investments	472,642	605,894
Cash and cash equivalents	723,784	1,434,045
Coinsurance deposits	4,402,849	4,347,990
Counterparty collateral	124,778	186,108
Liabilities
Policy benefit reserves	47,137,678	46,344,931
Single premium immediate annuity (SPIA) benefit reserves	288,991	292,153
Notes payable	506,345	521,800
Subordinated debentures	229,588	244,117
Amounts due under repurchase agreements	137,223	0
Fair Value [Member] \| Interest Rate Caps [Member]
Assets
Interest rate derivative assets	890	415
Fair Value [Member] \| Interest Rate Swap [Member]
Assets
Interest rate derivative assets	427	0
Liabilities
Interest rate derivative liabilities	$ 0	$ 789

Fair Values of Financial Instruments (Assumptions Used in Estimating Fair Value) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Expected cost of annual call options	3.10%	3.10%
Mortality rate assumption	65.00%
Fixed Annuity [Member] \| Minimum [Member] \| Contract Duration (Years), Group 1 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	1 year	1 year
Fixed Annuity [Member] \| Minimum [Member] \| Contract Duration (Years), Group 2 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	6 years	6 years
Fixed Annuity [Member] \| Minimum [Member] \| Contract Duration (Years), Group 3 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	11 years	11 years
Fixed Annuity [Member] \| Minimum [Member] \| Contract Duration (Years), Group 4 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	16 years	16 years
Fixed Annuity [Member] \| Minimum [Member] \| Contract Duration (Years), Group 5 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	20 years	20 years
Fixed Annuity [Member] \| Maximum [Member] \| Contract Duration (Years), Group 1 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	5 years	5 years
Fixed Annuity [Member] \| Maximum [Member] \| Contract Duration (Years), Group 2 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	10 years	10 years
Fixed Annuity [Member] \| Maximum [Member] \| Contract Duration (Years), Group 3 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	15 years	15 years
Fixed Annuity [Member] \| Maximum [Member] \| Contract Duration (Years), Group 4 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Contract duration (years)	20 years	20 years
Fixed Annuity [Member] \| Average [Member] \| Contract Duration (Years), Group 1 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Average lapse rates	2.11%	1.83%
Average partial withdrawal rates	3.33%	3.32%
Fixed Annuity [Member] \| Average [Member] \| Contract Duration (Years), Group 2 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Average lapse rates	7.30%	7.01%
Average partial withdrawal rates	3.33%	3.32%
Fixed Annuity [Member] \| Average [Member] \| Contract Duration (Years), Group 3 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Average lapse rates	11.33%	11.31%
Average partial withdrawal rates	3.34%	3.34%
Fixed Annuity [Member] \| Average [Member] \| Contract Duration (Years), Group 4 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Average lapse rates	11.91%	11.96%
Average partial withdrawal rates	3.24%	3.20%
Fixed Annuity [Member] \| Average [Member] \| Contract Duration (Years), Group 5 [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Average lapse rates	11.58%	11.62%
Average partial withdrawal rates	3.21%	3.20%

Fair Values of Financial Instruments (Reconciliation of Beginning and Ending Balances of Level 3 Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 8,790,427	$ 6,563,288
Premiums less benefits	549,153	411,502
Change in fair value, net	(1,106,023)	76,210
Ending balance	$ 8,233,557	$ 7,051,000

Investments (Narrative) (Details) $ in Thousands	3 Months Ended
Investments (Narrative) (Details) $ in Thousands	Mar. 31, 2018 USD ($) Securities	Mar. 31, 2017 USD ($)	Dec. 31, 2017 Securities
Investments [Abstract]
Fixed income securities with call features, percentage	37.00%
Fixed income securities with call features, currently callable, percentage	2.70%
Fixed income securities with call features, currently callable, amount	$ 1,200,000
Fixed income securities with call features, callable during next 12 months, percentage	0.20%
Fixed income securities with call features, callable during next 12 months, amount	$ 111,200
Fixed income securities with call features, not callable until within 6 months of stated maturity, percentage	74.00%
Percentage of fixed maturity portfolio rated investment grade based on NAIC designations	97.00%		97.00%
Number of individual securities with unrealized losses \| Securities	1,902		955
Percentage of unrealized losses on fixed maturity securities where securities are rated investment grade	88.00%		83.00%
Investment Holdings [Line Items]
Scheduled principal repayments, calls and tenders for available for sale securities	$ 265,837	$ 517,301
Available For Sale Securities [Member]
Investment Holdings [Line Items]
Proceeds from sales of available for sale securities	85,500	186,500
Fixed Maturity Securities [Member]
Investment Holdings [Line Items]
Scheduled principal repayments, calls and tenders for available for sale securities	$ 180,400	$ 330,800

Investments (Schedule of Amortized Cost and Fair Value of Fixed Maturity Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Held for investment, amortized cost	$ 77,043	$ 77,041
Held for investment	69,441	76,460
Fixed Maturity Securities [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	44,510,813	43,116,759
Available for sale, gross unrealized gains	1,664,524	2,525,131
Available for sale, gross unrealized losses	(623,989)	(268,901)
Available for sale, fair value	45,551,348	45,372,989
Fixed Maturity Securities [Member] \| United States Government Full Faith and Credit [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	11,696	11,861
Available for sale, gross unrealized gains	110	162
Available for sale, gross unrealized losses	(373)	(147)
Available for sale, fair value	11,433	11,876
Fixed Maturity Securities [Member] \| United States Government Sponsored Agencies [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	1,308,312	1,308,290
Available for sale, gross unrealized gains	21,134	28,457
Available for sale, gross unrealized losses	(59,340)	(31,730)
Available for sale, fair value	1,270,106	1,305,017
Fixed Maturity Securities [Member] \| United States Municipalities, States and Territories [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	3,853,098	3,804,360
Available for sale, gross unrealized gains	296,762	366,048
Available for sale, gross unrealized losses	(12,855)	(3,596)
Available for sale, fair value	4,137,005	4,166,812
Fixed Maturity Securities [Member] \| Foreign Government Obligations [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	227,617	228,214
Available for sale, gross unrealized gains	8,502	13,171
Available for sale, gross unrealized losses	(4,448)	(2,025)
Available for sale, fair value	231,671	239,360
Fixed Maturity Securities [Member] \| Corporate Securities [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	28,801,351	28,127,653
Available for sale, gross unrealized gains	1,186,607	1,897,005
Available for sale, gross unrealized losses	(403,830)	(145,687)
Available for sale, fair value	29,584,128	29,878,971
Held for investment, amortized cost	77,043	77,041
Held for investment, gross unrealized gains	0	0
Held for investment, gross unrealized losses	(7,602)	(581)
Held for investment	69,441	76,460
Fixed Maturity Securities [Member] \| Residential Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	1,044,032	1,028,484
Available for sale, gross unrealized gains	65,581	79,554
Available for sale, gross unrealized losses	(7,004)	(2,471)
Available for sale, fair value	1,102,609	1,105,567
Fixed Maturity Securities [Member] \| Commercial Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	5,685,290	5,531,922
Available for sale, gross unrealized gains	33,098	82,768
Available for sale, gross unrealized losses	(121,506)	(69,840)
Available for sale, fair value	5,596,882	5,544,850
Fixed Maturity Securities [Member] \| Other Asset Backed Securities [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost	3,579,417	3,075,975
Available for sale, gross unrealized gains	52,730	57,966
Available for sale, gross unrealized losses	(14,633)	(13,405)
Available for sale, fair value	$ 3,617,514	3,120,536
Equity Securities [Member]
Investment Holdings [Line Items]
Available for sale, amortized cost		292,429
Available for sale, gross unrealized gains		0
Available for sale, gross unrealized losses		0
Available for sale, fair value		$ 292,429

Investments (Fixed Maturity Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Available for sale securities, due in one year or less, amortized cost	$ 218,825
Available for sale securities, due after one year through five years, amortized cost	5,615,360
Available for sale securities, due after five years through ten years, amortized cost	10,439,109
Available for sale securities, due after ten years through twenty years, amortized cost	9,188,746
Available for sale securities, due after twenty years, amortized cost	8,740,034
Available for sale securities, securities with a single maturity date, amortized cost	34,202,074
Available for sale securities, amortized cost	44,510,813	$ 43,116,759
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available for sale securities, due in one year or less, fair value	223,487
Available for sale securities, due after one year through five years, fair value	5,673,765
Available for sale securities, due after five years through ten years, fair value	10,428,466
Available for sale securities, due after ten years through twenty years, fair value	9,774,966
Available for sale securities, due after twenty years, fair value	9,133,659
Available for sale securities, securities with a single maturity date, fair value	35,234,343
Available for sale securities, fair value	45,551,348	45,372,989
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held for investment securities, due in one year or less, amortized cost	0
Held for investment securities, due after one year through five years, amortized cost	0
Held for investment securities, due after five years through ten years, amortized cost	0
Held for investment securities, due after ten years through twenty years, amortized cost	0
Held for investment securities, due after twenty years, amortized cost	77,043
Held for investment securities, securities with a single maturity date, amortized cost	77,043
Held for investment, amortized cost	77,043	77,041
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Held for investment securities, due in one year or less, fair value	0
Held for investment securities, due after one year through five years, fair value	0
Held for investment securities, due after five years through ten years, fair value	0
Held for investment securities, due after ten years through twenty years, fair value	0
Held for investment securities, due after twenty years, fair value	69,441
Held for investment securities, securities with a single maturity date, fair value	69,441
Held for investment	69,441	$ 76,460
Residential Mortgage Backed Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Available for sale securities, securities without a single maturity date, amortized cost	1,044,032
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available for sale securities, securities without a single maturity date, fair value	1,102,609
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held for investment securities, securities without a single maturity date, amortized cost	0
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Held for investment securities, securities without a single maturity date, fair value	0
Commercial Mortgage Backed Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Available for sale securities, securities without a single maturity date, amortized cost	5,685,290
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available for sale securities, securities without a single maturity date, fair value	5,596,882
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held for investment securities, securities without a single maturity date, amortized cost	0
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Held for investment securities, securities without a single maturity date, fair value	0
Other Asset Backed Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Available for sale securities, securities without a single maturity date, amortized cost	3,579,417
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available for sale securities, securities without a single maturity date, fair value	3,617,514
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held for investment securities, securities without a single maturity date, amortized cost	0
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Held for investment securities, securities without a single maturity date, fair value	$ 0

Investments (Net Unrealized Gains on Available for Sale Fixed Maturity Securities Reported as a Separate Component of Stockholders' Equity) (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Schedule of Available-for-sale Securities [Line Items]

Net unrealized gains on available for sale fixed maturity securities

$ 1,040,535

$ 2,256,230

Adjustments for assumed changes in amortization of deferred policy acquisition costs and deferred sales inducements

(562,755)

(1,206,078)

Deferred income tax valuation allowance reversal

22,534

Deferred income tax expense

^[1]

(100,332)

(348,087)

Net unrealized gains reported as accumulated other comprehensive income

399,982

724,599

Accounting Standards Update 2018-02 [Member]

Schedule of Available-for-sale Securities [Line Items]

New accounting pronouncement, effect of adoption, quantification

$ 128,000

[1]

December 31, 2017 includes $128 million related to the impact of Tax Reform that was reclassified between accumulated other comprehensive income and retained earnings within our consolidated balance sheet during the first quarter of 2018. For more information regarding the reclassification, see Note 1 to our unaudited consolidated financial statements.

Investments (Schedule of Credit Quality of Fixed Maturity Portfolio by NAIC Designation) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Amortized cost	$ 44,587,856	$ 43,193,800
Fair value	45,620,789	45,449,449
NAIC, Class 1 Designation [Member]
Investment Holdings [Line Items]
Amortized cost	27,142,276	26,669,427
Fair value	27,984,297	28,274,379
NAIC, Class 2 Designation [Member]
Investment Holdings [Line Items]
Amortized cost	15,897,296	15,198,551
Fair value	16,147,267	15,869,219
NAIC, Class 3 Designation [Member]
Investment Holdings [Line Items]
Amortized cost	1,350,395	1,161,737
Fair value	1,316,146	1,157,420
NAIC, Class 4 Designation [Member]
Investment Holdings [Line Items]
Amortized cost	170,754	134,838
Fair value	145,085	117,542
NAIC, Class 5 Designation [Member]
Investment Holdings [Line Items]
Amortized cost	17,108	17,015
Fair value	19,926	20,927
NAIC, Class 6 Designation [Member]
Investment Holdings [Line Items]
Amortized cost	10,027	12,232
Fair value	$ 8,068	$ 9,962

Investments (Gross Unrealized Losses on Investments, By Category and Length of Time) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	$ 13,452,495	$ 3,999,294
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(282,536)	(47,884)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	4,695,940	4,815,325
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(341,453)	(221,017)
Available for sale securities, continuous unrealized loss position, total, fair value	18,148,435	8,814,619
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(623,989)	(268,901)
United States Government Full Faith and Credit [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	3,193	1,565
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(50)	(10)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	6,380	6,731
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(323)	(137)
Available for sale securities, continuous unrealized loss position, total, fair value	9,573	8,296
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(373)	(147)
United States Government Sponsored Agencies [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	74,632	44,794
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(1,513)	(180)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	932,691	958,965
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(57,827)	(31,550)
Available for sale securities, continuous unrealized loss position, total, fair value	1,007,323	1,003,759
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(59,340)	(31,730)
United States Municipalities, States and Territories [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	224,928	44,736
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(5,000)	(128)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	124,097	128,499
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(7,855)	(3,468)
Available for sale securities, continuous unrealized loss position, total, fair value	349,025	173,235
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(12,855)	(3,596)
Foreign Government Obligations [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	127,620	49,663
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(2,442)	(337)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	12,297	12,625
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(2,006)	(1,688)
Available for sale securities, continuous unrealized loss position, total, fair value	139,917	62,288
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(4,448)	(2,025)
Corporate Securities [Member] \| Finance, Insurance and Real Estate Sectors [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	1,980,979	456,244
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(46,008)	(5,135)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	599,683	600,655
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(48,915)	(28,043)
Available for sale securities, continuous unrealized loss position, total, fair value	2,580,662	1,056,899
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(94,923)	(33,178)
Corporate Securities [Member] \| Manufacturing, Construction and Mining [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	1,378,585	222,985
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(29,518)	(3,475)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	229,805	231,196
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(17,840)	(10,849)
Available for sale securities, continuous unrealized loss position, total, fair value	1,608,390	454,181
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(47,358)	(14,324)
Corporate Securities [Member] \| Utilities and Related Sectors [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	1,830,012	395,183
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(41,549)	(4,099)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	239,209	249,416
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(18,121)	(8,901)
Available for sale securities, continuous unrealized loss position, total, fair value	2,069,221	644,599
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(59,670)	(13,000)
Corporate Securities [Member] \| Wholesale/Retail Trade [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	755,307	152,941
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(16,446)	(1,249)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	173,229	178,635
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(16,809)	(11,371)
Available for sale securities, continuous unrealized loss position, total, fair value	928,536	331,576
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(33,255)	(12,620)
Corporate Securities [Member] \| Services, Media and Other [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	3,498,221	729,124
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(85,932)	(19,000)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	855,680	891,654
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(82,692)	(53,565)
Available for sale securities, continuous unrealized loss position, total, fair value	4,353,901	1,620,778
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(168,624)	(72,565)
Corporate Securities [Member] \| Insurance [Member]
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Held for investment securities, continuous unrealized loss position, less than 12 months, fair value	0	0
Held for investment securities, continuous unrealized loss position, less than 12 months, unrealized losses	0	0
Held for investment securities, continuous unrealized loss position, 12 months or longer, fair value	69,441	76,460
Held for investment securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(7,602)	(581)
Held for investment securities, continuous unrealized loss position, total, fair value	69,441	76,460
Held for investment securities, continuous unrealized loss position, total, unrealized losses	(7,602)	(581)
Residential Mortgage Backed Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	286,561	39,771
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(4,535)	(387)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	24,870	32,917
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(2,469)	(2,084)
Available for sale securities, continuous unrealized loss position, total, fair value	311,431	72,688
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(7,004)	(2,471)
Commercial Mortgage Backed Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	2,495,283	1,096,757
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(43,167)	(10,385)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	1,310,142	1,306,437
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(78,339)	(59,455)
Available for sale securities, continuous unrealized loss position, total, fair value	3,805,425	2,403,194
Available for sale securities, continuous unrealized loss position, total, unrealized losses	(121,506)	(69,840)
Other Asset Backed Securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale securities, continuous unrealized loss position, less than 12 months, fair value	797,174	765,531
Available for sale securities, continuous unrealized loss position, less than 12 months, unrealized losses	(6,376)	(3,499)
Available for sale securities, continuous unrealized loss position, 12 months or longer, fair value	187,857	217,595
Available for sale securities, continuous unrealized loss position, 12 months or longer, unrealized losses	(8,257)	(9,906)
Available for sale securities, continuous unrealized loss position, total, fair value	985,031	983,126
Available for sale securities, continuous unrealized loss position, total, unrealized losses	$ (14,633)	$ (13,405)

Investments (Changes in Net Unrealized Gains on Investments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Investment Holdings [Line Items]
Fixed maturity securities held for investment carried at amortized cost	$ (7,021)	$ (1,976)
Investments carried at fair value, available for sale	(1,215,695)	281,081
Adjustment for effect on other balance sheet accounts:
Deferred policy acquisition costs and deferred sales inducements	643,323	(150,962)
Deferred income tax asset/liability	120,201	(45,542)
Total adjustment for effect on other balance sheet accounts	763,524	(196,504)
Change in net unrealized gains on investments carried at fair value	(452,171)	84,577
Fixed Maturity Securities [Member]
Investment Holdings [Line Items]
Investments carried at fair value, available for sale	(1,215,695)	281,094
Equity Securities [Member]
Investment Holdings [Line Items]
Investments carried at fair value, available for sale	$ 0	$ (13)

Investments (Net Realized Gains (Losses) on Invesments, Excluding Other Than Temporary Impairments) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Gain (Loss) on Investments [Line Items]
Net realized gains (losses) on investments, excluding other than temporary impairment (OTTI) losses	$ 302	$ 2,338
Fixed Maturity Securities [Member]
Gain (Loss) on Investments [Line Items]
Gross realized gains	1,382	5,572
Gross realized losses	(2,102)	(3,563)
Gross realized gains (losses), excluding other than temporary impairments	(720)	2,009
Other Investments [Member]
Gain (Loss) on Investments [Line Items]
Gain on sale of real estate	0	29
Mortgage Loans on Real Estate [Member]
Gain (Loss) on Investments [Line Items]
Decrease in allowance for credit losses	300	300
Recovery of specific allowance	722	0
Change in allowance for credit losses and recoveries	$ 1,022	$ 300

Investments (Significant Assumptions in Determining Credit Loss Component of Other Than Temporary Impairment on Residential Mortgage Backed Securities) (Details) - Residential Mortgage Backed Securities [Member] - Prime Sector [Member]	3 Months Ended
	Mar. 31, 2017
Vintage Year 2005 [Member] \| Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.70%
Default rate	8.00%
Loss severity	50.00%
Vintage Year 2005 [Member] \| Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	7.70%
Default rate	8.00%
Loss severity	50.00%
Vintage Year 2007 [Member] \| Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	6.20%
Default rate	15.00%
Loss severity	50.00%
Vintage Year 2007 [Member] \| Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Discount rate	6.30%
Default rate	18.00%
Loss severity	60.00%

Investments (Other Than Temporary Impairments by Asset Type) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) Securities	Mar. 31, 2017 USD ($) Securities
Other than Temporary Impairment Losses, Investments [Abstract]
Total OTTI losses	$ (907)	$ 0
Portion of OTTI losses recognized in (from) other comprehensive income	0	(141)
Net OTTI losses recognized in operations	$ (907)	$ (141)
Corporate Securities [Member] \| Consumer Discretionary [Member]
Other than Temporary Impairment Losses, Investments [Abstract]
Other than temporary impairment, number of securities \| Securities	1
Total OTTI losses	$ (907)
Portion of OTTI losses recognized in (from) other comprehensive income	0
Net OTTI losses recognized in operations	$ (907)
Residential Mortgage Backed Securities [Member]
Other than Temporary Impairment Losses, Investments [Abstract]
Other than temporary impairment, number of securities \| Securities		3
Total OTTI losses		$ 0
Portion of OTTI losses recognized in (from) other comprehensive income		(141)
Net OTTI losses recognized in operations		$ (141)

Investments (Cumulative Credit Loss Portion of Other Than Temporary Impairment Recognized in Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Investments [Abstract]
Cumulative credit loss at beginning of period	$ (157,066)	$ (166,375)
Credit losses on securities for which OTTI has not previously been recognized	(907)	0
Additional credit losses on securities for which OTTI has previously been recognized	0	(141)
Accumulated losses on securities that were disposed of during the period	3,900	13,939
Cumulative credit loss at end of period	$ (154,073)	$ (152,577)

Investments (Cumulative Noncredit Portion of Other Than Temporary Impairment Recognized in Other Comprehensive Income and Change in Fair Value Since Other Than Temporary Impairment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Amortized cost	$ 305,349	$ 315,164
OTTI recognized in other comprehensive income	(173,411)	(173,974)
Change in fair value since OTTI was recognized	207,100	210,484
Fair value	339,038	351,674
Corporate Securities [Member]
Investment Holdings [Line Items]
Amortized cost	17,947	13,015
OTTI recognized in other comprehensive income	(3,700)	(4,263)
Change in fair value since OTTI was recognized	10,012	10,739
Fair value	24,259	19,491
Residential Mortgage Backed Securities [Member]
Investment Holdings [Line Items]
Amortized cost	282,835	297,582
OTTI recognized in other comprehensive income	(168,355)	(168,355)
Change in fair value since OTTI was recognized	198,719	201,620
Fair value	313,199	330,847
Other Asset Backed Securities [Member]
Investment Holdings [Line Items]
Amortized cost	4,567	4,567
OTTI recognized in other comprehensive income	(1,356)	(1,356)
Change in fair value since OTTI was recognized	(1,631)	(1,875)
Fair value	$ 1,580	$ 1,336

Mortgage Loans on Real Estate (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) portfolio_segment	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)
Mortgage Loans on Real Estate [Abstract]
Number of portfolio segments that make up financing receivables \| portfolio_segment	1
Real estate owned	$ 0		$ 0
Impaired mortgage loans, workout terms, interest only payments, six month terms	6 months
Impaired mortgage loans, workout terms, interest only payments, twelve month terms	12 months
Impaired mortgage loans, workout terms, cash flow sweep, number of months	12 months
Number of days past due, non-accrual status	90 days
Outstanding principal of loans in a non-accrual status	$ 0	$ 2,200
Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Number of days past due, delinquent status	60 days
Commercial Real Estate Portfolio Segment [Member]
Mortgage Loans on Real Estate [Line Items]
Commitments outstanding	$ 51,700

Mortgage Loans on Real Estate (Summary of Mortgage Loan Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Mortgage Loans on Real Estate [Abstract]
Principal outstanding	$ 2,707,352	$ 2,674,315
Loan loss allowance	(6,496)	(7,518)
Deferred prepayment fees	(1,219)	(1,266)
Mortgage loans on real estate	$ 2,699,637	$ 2,665,531

Mortgage Loans on Real Estate (Mortgage Loan Portfolio Summarized by Geographic Region and Property Type) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 2,707,352	$ 2,674,315
Percent	100.00%	100.00%
East [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 563,593	$ 548,067
Percent	20.80%	20.50%
Middle Atlantic [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 166,782	$ 163,485
Percent	6.20%	6.10%
Mountain [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 317,872	$ 308,486
Percent	11.70%	11.50%
New England [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 12,146	$ 12,265
Percent	0.50%	0.50%
Pacific [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 482,593	$ 466,030
Percent	17.80%	17.40%
South Atlantic [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 613,999	$ 609,736
Percent	22.70%	22.80%
West North Central [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 315,339	$ 324,808
Percent	11.60%	12.20%
West South Central [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 235,028	$ 241,438
Percent	8.70%	9.00%
Office [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 270,066	$ 283,926
Percent	10.00%	10.60%
Medical Office [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 32,902	$ 34,338
Percent	1.20%	1.30%
Retail [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 1,051,749	$ 1,040,028
Percent	38.80%	38.90%
Industrial/Warehouse [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 703,892	$ 677,770
Percent	26.00%	25.30%
Apartment [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 471,097	$ 462,897
Percent	17.40%	17.30%
Mixed Use/Other [Member]
Mortgage Loans on Real Estate [Line Items]
Principal outstanding	$ 177,646	$ 175,356
Percent	6.60%	6.60%

Mortgage Loans on Real Estate (Allowance for Loan Losses Rollforward) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning allowance balance	$ (7,518)
Ending allowance balance	(6,496)
Specific Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning allowance balance	(1,418)	$ (1,327)
Charge-offs	0	0
Recoveries	722	0
Change in provision for credit losses	0	0
Ending allowance balance	(696)	(1,327)
General Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning allowance balance	(6,100)	(7,100)
Charge-offs	0	0
Recoveries	0	0
Change in provision for credit losses	300	300
Ending allowance balance	$ (5,800)	$ (6,800)

Mortgage Loans on Real Estate (Impaired Mortgage Loans on Real Estate by Basis of Impairment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Mortgage Loans on Real Estate [Abstract]
Individually evaluated for impairment	$ 3,186	$ 5,445
Collectively evaluated for impairment	2,704,166	2,668,870
Principal outstanding	$ 2,707,352	$ 2,674,315

Mortgage Loans on Real Estate (Mortgage Loans by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Mortgage Loans on Real Estate [Abstract]
Performing	$ 2,705,957	$ 2,670,657
In workout	1,395	1,436
Collateral dependent	0	2,222
Principal outstanding	$ 2,707,352	$ 2,674,315

Mortgage Loans on Real Estate (Schedule of Financing Receivables Past Due) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial mortgage loans, past due	$ 0	$ 0
Commercial mortgage loans, current	2,707,352	2,672,093
Commercial mortgage loans, collateral dependent receivables	0	2,222
Principal outstanding	2,707,352	2,674,315
30 to 59 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial mortgage loans, past due	0	0
60 to 89 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial mortgage loans, past due	0	0
90 Days and Over [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial mortgage loans, past due	$ 0	$ 0

Mortgage Loans on Real Estate (Schedule of Impaired Financing Receivables) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Mortgage loans with an allowance, recorded investment	$ 2,490		$ 4,027
Mortgage loans with no related allowance, recorded investment	1,395		1,436
Impaired mortgage loans, recorded investment	3,885		5,463
Mortgage loans with an allowance, unpaid principal balance	3,186		5,445
Mortgage loans with no related allowance, unpaid principal balance	1,395		1,436
Impaired mortgage loans, unpaid principal balance	4,581		6,881
Mortgage loans with an allowance, related allowance	(696)		$ (1,418)
Mortgage loans with an allowance, average recorded investment	2,509	$ 3,291
Mortgage loans with no related allowance, average recorded investment	1,415	1,572
Impaired mortgage loans, average recorded investment	3,924	4,863
Mortgage loans with an allowance, interest income recognized	50	72
Mortgage loans with no related allowance, interest income recognized	21	23
Impaired mortgage loans, interest income reoognized	$ 71	$ 95

Mortgage Loans on Real Estate (Troubled Debt Restructurings) (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($) loans	Dec. 31, 2017 USD ($) loans
Financing Receivable, Modifications [Line Items]
Number of TDRs \| loans	2	2
Principal balance outstanding	$ 4,840	$ 4,880
Specific loan loss allowance	(467)	(467)
Net carrying amount	$ 4,373	$ 4,413
South Atlantic [Member]
Financing Receivable, Modifications [Line Items]
Number of TDRs \| loans	1	1
Principal balance outstanding	$ 2,930	$ 2,947
Specific loan loss allowance	0	0
Net carrying amount	$ 2,930	$ 2,947
East North Central [Member]
Financing Receivable, Modifications [Line Items]
Number of TDRs \| loans	1	1
Principal balance outstanding	$ 1,910	$ 1,933
Specific loan loss allowance	(467)	(467)
Net carrying amount	$ 1,443	$ 1,466

Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative collateral	$ 800.0	$ 1,600.0
Credit risk, maximum exposure	$ 60.2	$ 11.9
Call Options [Member]
Derivative [Line Items]
Derivative, term of contract	1 year
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, term of contract	7 years
Interest Rate Caps [Member]
Derivative [Line Items]
Derivative, term of contract	7 years
Interest Rate Caps [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Derivative [Line Items]
Derivative, cap interest rate	2.50%

Derivative Instruments (Fair Value of Derivative Instruments as Presented in the Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative assets	$ 847,741	$ 1,568,380
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	849,058	1,568,795
Derivative liabilities	8,233,557	8,791,216
Call Options [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	847,741	1,568,380
Interest Rate Caps [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	890	415
Interest Rate Swap [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	427	0
Derivative liabilities	0	789
Fixed Index Annuities - Embedded Derivatives [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 8,233,557	$ 8,790,427

Derivative Instruments (Change in Fair Value of Derivatives Included in the Consolidated Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	$ (451,083)	$ 386,533
Change in fair value of embedded derivatives	(867,232)	224,170
Call Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	(452,598)	386,736
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	1,040	75
Interest Rate Caps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	475	(278)
Fixed Index Annuities - Embedded Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	(1,106,023)	76,210
Other Changes in Difference Between Policy Benefit Reserves Computed Using Derivative Accounting Vs. Long-Duration Contracts Accounting [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	$ 238,791	$ 147,960

Derivative Instruments (Derivative Call Options, Notional Amount and Fair Value, by Counterparty) (Details) - Call Options [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amount	$ 36,862,422	$ 35,498,003
Derivative instruments	847,741	1,568,380
Bank of America [Member]
Derivative [Line Items]
Notional amount	5,522,691	4,645,366
Derivative instruments	91,549	237,955
Barclays [Member]
Derivative [Line Items]
Notional amount	3,784,024	4,135,537
Derivative instruments	89,471	154,127
BNP Paribas [Member]
Derivative [Line Items]
Notional amount	935,091	1,411,989
Derivative instruments	21,769	73,650
Canadian Imperial Bank of Commerce [Member]
Derivative [Line Items]
Notional amount	4,179,179	2,808,030
Derivative instruments	101,280	84,268
Citibank, N.A. [Member]
Derivative [Line Items]
Notional amount	4,422,448	4,104,666
Derivative instruments	77,256	219,900
Credit Suisse [Member]
Derivative [Line Items]
Notional amount	3,020,434	3,538,855
Derivative instruments	52,130	137,384
J.P. Morgan [Member]
Derivative [Line Items]
Notional amount	2,118,331	1,753,649
Derivative instruments	85,080	109,689
Morgan Stanley [Member]
Derivative [Line Items]
Notional amount	3,244,428	3,408,179
Derivative instruments	40,096	184,323
Royal Bank of Canada [Member]
Derivative [Line Items]
Notional amount	3,158,242	3,027,469
Derivative instruments	96,854	104,141
Societe Generale [Member]
Derivative [Line Items]
Notional amount	71,401	0
Derivative instruments	1,689	0
SunTrust [Member]
Derivative [Line Items]
Notional amount	2,080,242	2,331,168
Derivative instruments	65,445	90,399
Wells Fargo [Member]
Derivative [Line Items]
Notional amount	4,065,628	4,036,255
Derivative instruments	118,295	162,781
Exchange Traded [Member]
Derivative [Line Items]
Notional amount	260,283	296,840
Derivative instruments	$ 6,827	$ 9,763

Derivative Instruments (Interest Rate Swap) (Details) - Interest Rate Swap, Maturity Date, March 15, 2021, 2.415% [Member] - Interest Rate Swap [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amount	$ 85,500
Pay rate	2.415%
Derivative assets	$ 427
Derivative liabilities		$ (789)

Derivative Instruments (Interest Rate Caps) (Details) - Interest Rate Caps [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amount	$ 79,000
Derivative assets	890	$ 415
Interest Rate Caps, Maturity Date, July 7, 2021, 2.50% [Member]
Derivative [Line Items]
Notional amount	$ 40,000
Cap rate	2.50%
Derivative assets	$ 445	207
Interest Rate Caps, Maturity Date, July 8, 2021, 2.50% [Member]
Derivative [Line Items]
Notional amount	$ 12,000
Cap rate	2.50%
Derivative assets	$ 134	62
Interest Rate Caps, Maturity Date, July 29, 2021, 2.50% [Member]
Derivative [Line Items]
Notional amount	$ 27,000
Cap rate	2.50%
Derivative assets	$ 311	$ 146

Notes Payable and Amounts Due Under Repurchase Agreements (Schedule of Notes Payable) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Jun. 16, 2017
Debt Instrument [Line Items]
Notes payable	$ 494,215	$ 494,093
June 2027 Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	500,000	500,000	$ 500,000
Unamortized debt issue costs	(5,457)	(5,572)
Unamortized discount	$ (328)	$ (335)	$ (300)

Notes Payable and Amounts Due Under Repurchase Agreements (2027 Notes Narrative) (Details) - June 2027 Notes [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Jun. 16, 2017
Debt Instrument [Line Items]
Debt instrument, face amount	$ 500,000	$ 500,000	$ 500,000
Interest rate			5.00%
Unamortized discount	$ 328	$ 335	$ 300
Debt financing costs			$ 5,800

Notes Payable and Amounts Due Under Repurchase Agreements (Repurchase Agreements Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Debt Disclosure [Abstract]
Repurchase agreement, average borrowings	$ 7.6	$ 102.8
Repurchase agreement, maximum amount borrowed	$ 137.3	$ 274.5
Repurchase agreement, weighted average interest rate	1.63%	0.64%

Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	0	0
Earnings Per Share, Basic and Diluted [Line Items]
Net income - numerator for earnings per common share	$ 140,962	$ 53,939
Weighted average common shares outstanding (shares)	90,017,166	88,647,078
Denominator for earnings per common share - assuming dilution (shares)	91,139,348	89,975,612
Earnings per common share	$ 1.57	$ 0.61
Earnings per common share - assuming dilution	$ 1.55	$ 0.60
Stock Options and Deferred Compensation Agreements [Member]
Earnings Per Share, Basic and Diluted [Line Items]
Effect of dilutive securities: share-based payment arrangements (shares)	850,292	948,317
Restricted Stock and Restricted Stock Units [Member]
Earnings Per Share, Basic and Diluted [Line Items]
Effect of dilutive securities: share-based payment arrangements (shares)	271,890	380,217

Commitments and Contingencies (Narrative) (Details) $ in Millions	Mar. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Unfunded commitments to limited partnerships	$ 48.4
Unfunded commitments to secured bank loans	$ 6.2