INVESTMENT OPERATIONS (Tables)

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of major categories of net investment income

Major categories of net investment income are summarized as follows:

	For The Year Ended December 31,
	2019		2018		2017
	(Dollars In Thousands)
Fixed maturities	$	2,465,902	$	2,043,183	$	1,610,768
Equity securities	30,647		35,282		40,506
Mortgage loans	388,656		322,206		298,387
Investment real estate	1,045		1,778		2,405
Short-term investments	118,172		103,676		114,280
	3,004,422		2,506,125		2,066,346
Investment expenses	185,592		167,223		143,290
Net investment income	$	2,818,830	$	2,338,902	$	1,923,056

Summary of net realized investment gains (losses) for invested assets

Net realized investment gains (losses) for all other investments are summarized as follows:

	For The Year Ended December 31,
	2019		2018		2017
	(Dollars In Thousands)
Fixed maturities	$	47,711	$	9,851	$	12,783
Equity securities gains and losses(1)	46,989		(49,275)		(2,330)
Modco trading portfolio	247,331		(185,900)		119,206
Other investments	967		2,048		(8,572)
Realized gains (losses) - all other investments	342,998		(223,276)		121,087
Realized gains (losses) - derivatives	(131,459)		79,097		(137,041)
Realized investment gains (losses)	$	211,539	$	(144,179)	$	(15,954)
Net impairment losses recognized in earnings	$	(34,453)	$	(29,724)	$	(9,112)
(1) Beginning January 1, 2018, all changes in the fair value of equity securities are recorded as a realized gain (loss) as a result of the adoption of ASU No. 2016-01.

Gross realized gains and gross realized losses on investments available-for-sale (fixed maturities and short-term investments) are as follows:

	For The Year Ended December 31,
	2019		2018		2017
	(Dollars In Thousands)
Gross realized gains	$	61,608	$	28,034	$	18,868
Gross realized losses:
Impairments losses	$	(34,453)	$	(29,724)	$	(9,112)
Other realized losses	$	(13,897)	$	(18,183)	$	(8,257)

Schedule of fair value (proceeds) and gains (losses) on securities in an unrealized gain or loss position

The chart below summarizes the fair value proceeds and the gains (losses) realized on securities the Company sold that were in an unrealized gain position and an unrealized loss position.

	For The Year Ended December 31,
	2019		2018		2017
	(Dollars In Thousands)
Securities in an unrealized gain position:
Fair value proceeds	$	2,511,764	$	1,291,826	$	879,181
Gains realized	$	61,608	$	28,034	$	18,868
Securities in an unrealized loss position(1):
Fair value proceeds	$	542,733	$	472,371	$	185,157
Losses realized	$	(13,897)	$	(18,183)	$	(8,257)
(1) The Company made the decision to exit these holdings in conjunction with its overall asset liability management process.

The following table includes the gross unrealized losses and fair value of the Company’s investments that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2019:

	Less Than 12 Months				12 Months or More				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
	(Dollars In Thousands)
Residential mortgage-backed securities	$	851,333	$	(4,231)	$	220,843	$	(2,091)	$	1,072,176	$	(6,322)
Commercial mortgage-backed securities	371,945		(1,721)		115,566		(1,571)		487,511		(3,292)
Other asset-backed securities	482,547		(6,516)		214,058		(8,410)		696,605		(14,926)
U.S. government-related securities	383,451		(3,373)		353,517		(1,943)		736,968		(5,316)
Other government-related securities	22,962		(669)		6,230		(1,322)		29,192		(1,991)
States, municipalities, and political subdivisions	56,470		(1,001)		12,907		(229)		69,377		(1,230)
Corporate securities	3,176,489		(68,289)		2,886,648		(220,045)		6,063,137		(288,334)
Redeemable preferred stocks	—		—		16,689		(4,249)		16,689		(4,249)
	$	5,345,197	$	(85,800)	$	3,826,458	$	(239,860)	$	9,171,655	$	(325,660)

The following table includes the gross unrealized losses and fair value of the Company’s investments that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2018:

	Less Than 12 Months				12 Months or More				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
	(Dollars In Thousands)
Residential mortgage-backed securities	$	1,485,009	$	(31,302)	$	795,765	$	(30,633)	$	2,280,774	$	(61,935)
Commercial mortgage-backed securities	419,420		(7,398)		1,405,690		(49,602)		1,825,110		(57,000)
Other asset-backed securities	687,271		(30,963)		148,871		(4,435)		836,142		(35,398)
U.S. government-related securities	130,290		(4,668)		1,085,654		(41,054)		1,215,944		(45,722)
Other government-related securities	224,273		(15,207)		131,569		(18,583)		355,842		(33,790)
States, municipalities, and political subdivisions	1,004,262		(27,180)		1,129,152		(91,722)		2,133,414		(118,902)
Corporate securities	18,225,656		(966,825)		12,824,024		(1,411,415)		31,049,680		(2,378,240)
Redeemable preferred stocks	41,147		(4,467)		41,655		(7,093)		82,802		(11,560)
	$	22,217,328	$	(1,088,010)	$	17,562,380	$	(1,654,537)	$	39,779,708	$	(2,742,547)

Schedule of realized gains (losses) on equity securities

The chart below summarizes the realized gains (losses) on equity securities sold during the period and equity securities still held at the reporting date.

	For The Year Ended December 31,
	2019		2018
	(Dollars In Thousands)
Net gains (losses) recognized during the period on equity securities	$	46,989	$	(49,275)
Less: net gains (losses) recognized on equity securities sold during the period	$	(3,225)	$	(6,165)
Gains (losses) recognized during the period on equity securities still held	$	50,214	$	(43,110)

Schedule of amortized cost and fair value of the Company's investments classified as available-for-sale

The amortized cost and fair value of the Company’s investments classified as available-for-sale are as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value		Total OTTI Recognized in OCI(1)
	(Dollars In Thousands)
As of December 31, 2019
Fixed maturities:
Residential mortgage-backed securities	$	5,812,170	$	125,493	$	(6,322)	$	5,931,341	$	—
Commercial mortgage-backed securities	2,588,575		54,385		(3,292)		2,639,668		—
Other asset-backed securities	1,764,120		32,041		(14,926)		1,781,235		(7)
U.S. government-related securities	1,032,048		5,664		(5,316)		1,032,396		—
Other government-related securities	548,136		51,024		(1,991)		597,169		—
States, municipals, and political subdivisions	4,415,008		225,072		(1,230)		4,638,850		1,236
Corporate securities	44,493,799		2,603,636		(288,334)		46,809,101		(34,580)
Redeemable preferred stocks	87,237		3,677		(4,249)		86,665		—
	60,741,093		3,100,992		(325,660)		63,516,425		(33,351)
Short-term investments	1,229,651		—		—		1,229,651		—
	$	61,970,744	$	3,100,992	$	(325,660)	$	64,746,076	$	(33,351)
As of December 31, 2018
Fixed maturities:
Residential mortgage-backed securities	$	3,641,678	$	23,248	$	(61,935)	$	3,602,991	$	(18)
Commercial mortgage-backed securities	2,319,476		3,911		(57,000)		2,266,387		—
Other asset-backed securities	1,410,059		17,232		(35,398)		1,391,893		—
U.S. government-related securities	1,658,433		1,794		(45,722)		1,614,505		—
Other government-related securities	543,534		4,292		(33,790)		514,036		—
States, municipals, and political subdivisions	3,682,037		25,706		(118,902)		3,588,841		876
Corporate securities	38,467,380		112,438		(2,378,240)		36,201,578		(29,685)
Redeemable preferred stocks	94,362		—		(11,560)		82,802		—
	51,816,959		188,621		(2,742,547)		49,263,033		(28,827)
Short-term investments	635,375		—		—		635,375		—
	$	52,452,334	$	188,621	$	(2,742,547)	$	49,898,408	$	(28,827)

(1)These amounts are included in the gross unrealized gains and gross unrealized losses columns above.

Schedule of fair value of trading securities

The fair value of the investments held pursuant to these Modco arrangements are as follows:

	As of December 31,
	2019		2018
	(Dollars In Thousands)
Fixed maturities:
Residential mortgage-backed securities	$	209,521	$	241,836
Commercial mortgage-backed securities	201,284		188,925
Other asset-backed securities	143,361		159,907
U.S. government-related securities	47,067		59,794
Other government-related securities	28,775		44,207
States, municipals, and political subdivisions	293,791		286,413
Corporate securities	1,590,936		1,423,833
Redeemable preferred stocks	12,832		11,277
	2,527,567		2,416,192
Equity securities	6,656		9,892
Short-term investments	91,213		30,926
	$	2,625,436	$	2,457,010

Schedule of amortized cost and fair value of available-for-sale and held-to-maturity fixed maturities, by expected maturity

The amortized cost and fair value of available-for-sale and held-to-maturity fixed maturities as of December 31, 2019, by expected maturity, are shown below. Expected maturities of securities without a single maturity date are allocated based on estimated rates of prepayment that may differ from actual rates of prepayment.

	Available-for-sale				Held-to-maturity
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars In Thousands)
Due in one year or less	$	1,833,383	$	1,832,073	$	—	$	—
Due after one year through five years	10,513,141		10,732,319		—		—
Due after five years through ten years	13,423,688		14,018,121		—		—
Due after ten years	34,970,881		36,933,912		2,823,881		3,025,790
	$	60,741,093	$	63,516,425	$	2,823,881	$	3,025,790

Schedule of gain (loss) on investments

The chart below summarizes the Company’s other-than-temporary impairments of investments. All of the impairments were related to fixed maturities or equity securities.

	Fixed Maturities		Equity Securities		Total Securities
	(Dollars In Thousands)
For The Year Ended December 31, 2019
Other-than-temporary impairments	$	(67,161)	$	—	$	(67,161)
Non-credit impairment losses recorded in other comprehensive income	32,708		—		32,708
Net impairment losses recognized in earnings	$	(34,453)	$	—	$	(34,453)
For The Year Ended December 31, 2018
Other-than-temporary impairments	$	(56,578)	$	—	$	(56,578)
Non-credit impairment losses recorded in other comprehensive income	26,854		—		26,854
Net impairment losses recognized in earnings	$	(29,724)	$	—	$	(29,724)
For The Year Ended December 31, 2017
Other-than-temporary impairments	$	(1,332)	$	—	$	(1,332)
Non-credit impairment losses recorded in other comprehensive income	(7,780)		—		(7,780)
Net impairment losses recognized in earnings	$	(9,112)	$	—	$	(9,112)

Schedule of available-for-sale credit losses on fixed maturities held by the Company for which a portion of an other-than-temporary impairment was recognized in other comprehensive income

The following chart is a rollforward of available-for-sale credit losses on fixed maturities held by the Company for which a portion of an other-than-temporary impairment was recognized in other comprehensive income (loss):

	For The Year Ended December 31,
	2019		2018		2017
	(Dollars In Thousands)
Beginning balance	$	24,868	$	3,268	$	12,685
Additions for newly impaired securities	30,299		24,858		734
Additions for previously impaired securities	3,553		12		3,175
Reductions for previously impaired securities due to a change in expected cash flows	(21,332)		—		(12,726)
Reductions for previously impaired securities that were sold in the current period	(7,294)		(3,270)		(600)
Ending balance	$	30,094	$	24,868	$	3,268

Summary of change in unrealized gains (losses), net of income tax, on fixed maturity and equity securities, classified as available-for-sale

The change in unrealized gains (losses), net of income tax, on fixed maturities classified as available-for-sale is summarized as follows:

	For The Year Ended December 31,
	2019		2018		2017
	(Dollars In Thousands)
Fixed maturities	$	4,210,114	$	(2,032,573)	$	1,083,865

Schedule of amortized cost and fair value of the Company's investments classified as held-to-maturity

The amortized cost and fair value of the Company’s investments classified as held-to-maturity as of December 31, 2019 and 2018, are as follows:

	Amortized Cost		Gross Unrecognized Holding Gains		Gross Unrecognized Holding Losses		Fair Value		Total OTTI Recognized in OCI
As of December 31, 2019
	(Dollars In Thousands)
Fixed maturities:
Securities issued by affiliates:
Red Mountain LLC	$	795,881	$	81,022	$	—	$	876,903	$	—
Steel City LLC	2,028,000		120,887		—		2,148,887		—
	$	2,823,881	$	201,909	$	—	$	3,025,790	$	—

	Amortized Cost		Gross Unrecognized Holding Gains		Gross Unrecognized Holding Losses		Fair Value		Total OTTI Recognized in OCI
As of December 31, 2018
	(Dollars In Thousands)
Fixed maturities:
Securities issued by affiliates:
Red Mountain LLC	$	750,474	$	—	$	(81,657)	$	668,817	$	—
Steel City LLC	1,883,000		—		(4,607)		1,878,393		—
	$	2,633,474	$	—	$	(86,264)	$	2,547,210	$	—