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, 2025	Sep. 30, 2024		Sep. 30, 2025	Sep. 30, 2024
Premiums:
Direct	$ 473,746	$ 462,391		$ 1,412,099	$ 1,384,477
Assumed	18,511	29		44,533	92
Ceded	(349,110)	(365,331)		(1,051,299)	(1,100,377)
Net Premiums	143,147	97,089		405,333	284,192
Policy charges and fee income:
Direct	812,539	808,852		2,392,621	2,365,340
Assumed	197,209	220,781		557,860	719,389
Ceded	(607,855)	(620,866)		(1,679,626)	622,077
Net policy charges and fee income	401,893	408,767		1,270,855	3,706,806
Net investment income:
Direct	852,298	651,762		2,376,020	1,763,262
Assumed	328	333		967	996
Ceded	(13,232)	(13,403)		(39,544)	(40,253)
Net investment income	839,394	638,692		2,337,443	1,724,005
Asset administration fees:
Direct	80,153	83,659		235,386	246,123
Ceded	(28,230)	(27,231)		(81,416)	(77,950)
Net asset administration fees	51,923	56,428		153,970	168,173
Other income (loss):
Direct	179,919	332,233		469,525	461,980
Assumed	(20)	(75)		311	274
Ceded	73,460	56,618		200,010	282,635
Net other income (loss)	253,359	388,776	[1]	669,846	744,889	[1]
Realized investment gains (losses), net:
Direct	(248,294)	(552,741)		(1,100,639)	232,461
Assumed	734	14,552		32,085	77,736
Ceded	(100,309)	(113,329)		(205,053)	(159,772)
Realized investment gains (losses), net	(347,869)	(651,518)	[1]	(1,273,607)	150,425	[1]
Change in value of market risk benefits, net of related hedging gains (losses):
Direct	208,315	(214,414)		(454,586)	(188,598)
Assumed	1,551	(245)		1,442	2,277
Ceded	(93,688)	39,258		(42,918)	(167,267)
Net change in value of market risk benefits, net of related hedging gain (loss)	116,178	(175,401)	[1]	(496,062)	(353,588)	[2]
Policyholders’ benefits (including change in reserves):
Direct	1,094,549	855,117		3,158,486	2,765,937
Assumed	264,954	242,113		828,116	775,334
Ceded	(1,194,533)	(966,549)		(3,378,988)	831,697
Net policyholders’ benefits (including change in reserves	164,970	130,681		607,614	4,372,968
Change in estimates of liability for future policy benefits:
Direct	49,720	142,204		(75,824)	354,660
Assumed	8,022	17,025		(14,354)	81,893
Ceded	(44,062)	(156,795)		2,970	(452,298)
Net change in estimates of liability for future policy benefits	13,680	2,434		(87,208)	(15,745)
Interest credited to policyholders’ account balances:
Direct	444,614	332,064		1,054,666	941,448
Assumed	31,389	35,476		99,175	117,968
Ceded	(110,747)	(111,380)		(326,246)	(318,682)
Net interest credited to policyholders’ account balances	365,256	256,160	[1]	827,595	740,734	[1]
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(92,403)	(115,073)		(288,056)	(623,863)
Unaffiliated activity
Premiums:
Assumed	26	29		80	89
Ceded	(36,841)	(27,821)		(106,749)	(79,800)
Policy charges and fee income:
Assumed	393	429		1,052	1,057
Ceded	(78,663)	(45,692)		(886,426)	(132,662)
Net investment income:
Ceded	(371)	0		(1,233)	0
Asset administration fees:
Ceded	(6,281)	(7,151)		(18,925)	(21,474)
Other income (loss):
Assumed	(210)	(75)		(233)	378
Ceded	39,086	28,806		117,708	81,551
Realized investment gains (losses), net:
Assumed	734	14,552		32,085	77,736
Ceded	(72,741)	(100,167)		(143,328)	(120,807)
Change in value of market risk benefits, net of related hedging gains (losses):
Assumed	1,551	(245)		1,442	2,277
Ceded	(48,624)	5,318		1,722	(58,229)
Policyholders’ benefits (including change in reserves):
Assumed	76			310	216
Assumed		(145)
Ceded	(164,226)	(51,927)		(1,016,520)	(262,998)
Change in estimates of liability for future policy benefits:
Ceded	(16,543)	673		(33,782)	92,575
Interest credited to policyholders’ account balances:
Assumed	5,351	6,772		19,899	31,888
Ceded	$ (25,219)	$ 1		$ (74,513)	$ 0

[1] Amounts reflect revision to prior period Financial Statements. See Note 17 for additional information.

[2] Amounts reflect revision to prior period Financial Statements. See Note 17 for additional information.