Reinsurance (Reinsurance amounts included in the Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022		Sep. 30, 2023	Sep. 30, 2022
Premiums:
Direct	$ 457,967	$ 462,478		$ 1,396,506	$ 1,406,822
Assumed	32	(2,653)		(90)	(10,730)
Ceded	(372,859)	(398,109)		(1,144,655)	(1,210,547)
Net Premiums	85,140	61,716	[1]	251,761	185,545	[1]
Policy charges and fee income:
Direct	753,291	746,814		2,238,266	2,295,350
Assumed	151,927	149,564		453,006	455,114
Ceded	(558,737)	(526,432)		(1,594,764)	(1,892,583)
Net policy charges and fee income	346,481	369,946	[1]	1,096,508	857,881	[1]
Net investment income:
Direct	463,070	226,827		1,216,154	617,818
Assumed	338	349		1,024	1,167
Ceded	(2,544)	(16,414)		(13,789)	(36,795)
Net investment income	460,864	210,762		1,203,389	582,190
Asset administration fees:
Direct	81,422	84,959		242,730	271,071
Assumed	0	0		0	0
Ceded	(24,668)	(16,405)		(64,986)	(51,495)
Net asset administration fees	56,754	68,554		177,744	219,576
Other income (loss):
Direct	(89,144)	(181,634)		216,247	(855,885)
Assumed	116	3,059		(233)	550
Ceded	25,473	17,168		70,736	60,206
Net Other income (loss)	(63,555)	(161,407)	[1]	286,750	(795,129)	[1]
Realized investment gains (losses), net:
Direct	(492,184)	(44,847)		(826,822)	1,080,351
Assumed	(31,544)	122,364		189,400	(363,266)
Ceded	55,472	19,754		56,181	93,686
Realized investment gains (losses), net	(468,256)	97,271	[1]	(581,241)	810,771	[2]
Change in value of market risk benefits, net of related hedging gain (loss):
Direct	(54,544)	29,320		152,660	(698,317)
Assumed	283	0		(3,160)	0
Ceded	(193,210)	(109,398)		(415,656)	(537,098)
Net change in value of market risk benefits, net of related hedging gain (loss)	(247,471)	(80,078)	[1]	(266,156)	(1,235,415)	[2]
Policyholders’ benefits (including change in reserves):
Direct	912,588	880,240		2,639,868	2,460,564
Assumed	336,300	289,093		985,635	868,301
Ceded	(1,103,479)	(1,081,648)		(3,227,951)	(2,961,322)
Net policyholders’ benefits (including change in reserves	145,409	87,685	[1]	397,552	367,543	[1]
Change in estimates of liability for future policy benefits:
Direct	(44,155)	(69,944)		(61,510)	1,748,781
Assumed	(17,580)	(12,640)		8,071	676,754
Ceded	68,300	79,649		54,469	(2,382,670)
Change in estimates of liability for future policy benefits	6,565	(2,935)	[1]	1,030	42,865	[1]
Interest credited to policyholders’ account balances:
Direct	228,399	259,175		666,947	593,160
Assumed	33,602	(52,300)		100,065	49,803
Ceded	(98,927)	(109,226)		(299,900)	(324,377)
Net interest credited to policyholders’ account balances	163,074	97,649	[1]	467,112	318,586	[1]
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(57,368)	146,690		(280,393)	(71,962)
Unaffiliated
Premiums:
Assumed	32	(2,653)		(100)	(16,061)
Ceded	(13,942)	(10,036)		(47,319)	(32,606)
Policy charges and fee income:
Assumed	460	1,929		1,383	13,350
Ceded	(39,143)	(21,196)		(101,419)	(59,453)
Net investment income:
Ceded	10,109	(4,122)		23,022	195
Asset administration fees:
Ceded	(7,464)	0		(15,204)	0
Other income (loss):
Assumed	185	3,059		(53)	549
Ceded	7,887	1,622		17,540	1,622
Realized investment gains (losses), net:
Assumed	(31,544)	122,365		189,400	(159,280)
Ceded	41,007	19,601		40,378	92,377
Change in value of market risk benefits, net of related hedging gain (loss):
Assumed	283	0		(3,160)	0
Ceded	(70,693)	(20,174)		(150,791)	(106,676)
Policyholders’ benefits (including change in reserves):
Assumed	265	587		545	1,941
Ceded	(42,655)	(18,206)		(106,475)	(61,248)
Change in estimates of liability for future policy benefits:
Ceded	(1,407)	0		(1,823)	(6,594)
Interest credited to policyholders’ account balances:
Assumed	3,651	(83,932)		8,750	(86,713)
Ceded	$ 85	$ 0		$ 0	$ 0

[1] Prior period amounts adjusted for the implementation of ASU 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.

[2] Prior period amounts adjusted for the implementation of ASU 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.