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, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Premiums:
Direct	$ 462,458	$ 476,472	$ 922,086	$ 938,539
Assumed	30	34	63	(122)
Ceded	(367,567)	(386,541)	(735,046)	(771,796)
Net Premiums	94,921	89,965	187,103	166,621
Policy charges and fee income:
Direct	785,299	749,037	1,556,488	1,484,975
Assumed	239,838	148,479	498,608	301,079
Ceded	(636,303)	(533,980)	1,242,943	(1,036,027)
Net policy charges and fee income	388,834	363,536	3,298,039	750,027
Net investment income:
Direct	592,448	402,761	1,111,500	753,084
Assumed	333	343	663	686
Ceded	(12,788)	(10,029)	(26,850)	(11,245)
Net investment income	579,993	393,075	1,085,313	742,525
Asset administration fees:
Direct	79,776	80,952	162,464	161,308
Assumed	0	0	0	0
Ceded	(24,663)	(24,164)	(50,719)	(40,318)
Net asset administration fees	55,113	56,788	111,745	120,990
Other income (loss):
Direct	84,931	79,657	129,747	305,391
Assumed	24	(56)	349	(349)
Ceded	52,734	25,857	221,078	45,263
Net other income (loss)	137,689	105,458	351,174	350,305
Realized investment gains (losses), net:
Direct	765,146	(88,715)	777,502	(334,638)
Assumed	72,351	82,278	63,184	220,944
Ceded	1,385	14,131	21,196	709
Realized investment gains (losses), net	838,882	7,694	861,882	(112,985)
Change in value of market risk benefits, net of related hedging gain (loss):
Direct	(298,559)	174,084	15,327	207,204
Assumed	1,072	2,774	606	(3,443)
Ceded	15,304	(215,745)	(206,525)	(222,446)
Change in value of market risk benefits, net of related hedging gain (loss)	(282,183)	(38,887)	(190,592)	(18,685)
Policyholders’ benefits (including change in reserves):
Direct	909,374	848,495	1,910,820	1,727,280
Assumed	245,810	332,048	533,221	649,335
Ceded	(1,019,305)	(1,033,582)	1,798,246	(2,124,472)
Net policyholders’ benefits (including change in reserves	135,879	146,961	4,242,287	252,143
Change in estimates of liability for future policy benefits
Direct	72,870	31,146	212,456	(17,355)
Assumed	74,378	23,844	64,868	25,651
Ceded	(153,422)	(56,123)	(295,503)	(13,831)
Change in estimates of liability for future policy benefits	(6,174)	(1,133)	(18,179)	(5,535)
Interest credited to policyholders’ account balances:
Direct	297,194	215,973	575,584	438,548
Assumed	36,344	27,957	82,492	66,463
Ceded	(107,314)	(100,114)	(207,302)	(200,973)
Net interest credited to policyholders’ account balances	226,224	143,816	450,774	304,038
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(116,030)	(105,195)	(506,173)	(223,025)
Unaffiliated activity
Premiums:
Assumed	30	34	60	(132)
Ceded	(26,827)	(16,802)	(51,979)	(33,377)
Policy charges and fee income:
Assumed	356	383	628	923
Ceded	(44,958)	(38,338)	(86,970)	(62,276)
Net investment income:
Ceded	0	1,993	0	12,913
Asset administration fees:
Ceded	(7,007)	(7,740)	(14,323)	(7,740)
Other income (loss):
Assumed	24	55	453	(238)
Ceded	26,002	8,031	47,806	9,653
Realized investment gains (losses), net:
Assumed	72,351	82,278	63,184	220,944
Ceded	21,774	13,952	46,999	(629)
Change in value of market risk benefits, net of related hedging gain (loss):
Assumed	1,072	2,774	606	(3,443)
Ceded	34,461	(75,325)	(63,547)	(80,098)
Policyholders’ benefits (including change in reserves):
Assumed	28	189	361	280
Ceded	(64,243)	(36,118)	(211,071)	(63,820)
Change in estimates of liability for future policy benefits
Ceded	29	(416)	91,902	(416)
Interest credited to policyholders’ account balances:
Assumed	7,657	(2,370)	25,116	5,099
Ceded	$ (1)	$ (85)	$ (1)	$ (85)