Reinsurance (Reinsurance amounts included in the Statement of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022		Jun. 30, 2023	Jun. 30, 2022
Premiums:
Direct	$ 476,472	$ 470,923		$ 938,539	$ 944,344
Assumed	34	(9,474)		(122)	(8,077)
Ceded	(386,541)	(407,125)		(771,796)	(812,438)
Net Premiums	89,965	54,324	[1]	166,621	123,829	[1]
Policy charges and fee income:
Direct	749,037	757,637		1,484,975	1,548,536
Assumed	148,479	158,744		301,079	305,550
Ceded	(533,980)	(517,626)		(1,036,027)	(1,366,151)
Net policy charges and fee income	363,536	398,755	[1]	750,027	487,935	[1]
Net investment income:
Direct	402,761	195,480		753,084	390,991
Assumed	343	365		686	818
Ceded	(10,029)	(3,717)		(11,245)	(20,381)
Net investment income	393,075	192,128		742,525	371,428
Asset administration fees:
Direct	80,952	88,655		161,308	186,112
Assumed	0	0		0	0
Ceded	(24,164)	(16,865)		(40,318)	(35,090)
Net asset administration fees	56,788	71,790		120,990	151,022
Other income (loss):
Direct	79,657	(325,563)		305,391	(674,251)
Assumed	(56)	(2,548)		(349)	(2,509)
Ceded	25,857	21,472		45,263	43,038
Net Other income (loss)	105,458	(306,639)	[1]	350,305	(633,722)	[1]
Realized investment gains (losses), net:
Direct	(88,715)	614,376		(334,638)	1,125,198
Assumed	82,278	(281,646)		220,944	(485,630)
Ceded	14,131	27,489		709	73,932
Realized investment gains (losses), net	7,694	360,219	[1]	(112,985)	713,500	[2]
Change in value of market risk benefits, net of related hedging gain (loss):
Direct	174,084	(556,282)		207,204	(727,637)
Assumed	2,774	0		(3,443)	0
Ceded	(215,745)	(161,187)		(222,446)	(427,700)
Net change in value of market risk benefits, net of related hedging gain (loss)	(38,887)	(717,469)	[1]	(18,685)	(1,155,337)	[2]
Policyholders’ benefits (including change in reserves):
Direct	848,495	726,165		1,727,280	1,580,324
Assumed	332,048	326,171		649,335	579,208
Ceded	(1,033,582)	(957,887)		(2,124,472)	(1,879,674)
Net policyholders’ benefits (including change in reserves	146,961	94,449	[1]	252,143	279,858	[1]
Change in estimates of liability for future policy benefits:
Direct	31,146	1,828,707		(17,355)	1,818,725
Assumed	23,844	707,485		25,651	689,394
Ceded	(56,123)	(2,487,545)		(13,831)	(2,462,319)
Change in estimates of liability for future policy benefits	(1,133)	48,647	[1]	(5,535)	45,800	[1]
Interest credited to policyholders’ account balances:
Direct	215,973	188,115		438,548	333,985
Assumed	27,957	29,601		66,463	102,103
Ceded	(100,114)	(108,798)		(200,973)	(215,151)
Net interest credited to policyholders’ account balances	143,816	108,918	[1]	304,038	220,937	[1]
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(105,195)	(101,295)		(223,025)	(218,652)
Unaffiliated
Premiums:
Assumed	34	(13,448)		(132)	(13,408)
Ceded	(16,802)	(11,048)		(33,377)	(22,570)
Policy charges and fee income:
Assumed	383	11,421		923	11,421
Ceded	(38,338)	(19,959)		(62,276)	(38,257)
Net investment income:
Ceded	1,993	8,650		12,913	4,317
Asset administration fees:
Ceded	(7,740)	0		(7,740)	0
Other income (loss):
Assumed	55	(2,549)		(238)	(2,510)
Ceded	8,031	0		9,653	0
Realized investment gains (losses), net:
Assumed	82,278	(281,645)		220,944	(281,645)
Ceded	13,952	26,826		(629)	72,776
Change in value of market risk benefits, net of related hedging gain (loss):
Assumed	2,774	0		(3,443)	0
Ceded	(75,325)	(35,629)		(80,098)	(86,502)
Policyholders’ benefits (including change in reserves):
Assumed	189	1,245		280	1,354
Ceded	(36,118)	(24,551)		(63,820)	(43,042)
Change in estimates of liability for future policy benefits:
Ceded	(416)	(6,594)		(416)	(6,594)
Interest credited to policyholders’ account balances:
Assumed	(2,370)	(2,781)		5,099	(2,781)
Ceded	$ (85)	$ 0		$ (85)	$ 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.