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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Premiums:
Direct	$ 462,391	$ 457,967	$ 1,384,477	$ 1,396,506
Assumed	29	32	92	(90)
Ceded	(365,331)	(372,859)	(1,100,377)	(1,144,655)
Net Premiums	97,089	85,140	284,192	251,761
Policy charges and fee income:
Direct	808,852	753,291	2,365,340	2,238,266
Assumed	220,781	151,927	719,389	453,006
Ceded	(620,866)	(558,737)	622,077	(1,594,764)
Net policy charges and fee income	408,767	346,481	3,706,806	1,096,508
Net investment income:
Direct	651,762	463,070	1,763,262	1,216,154
Assumed	333	338	996	1,024
Ceded	(13,403)	(2,544)	(40,253)	(13,789)
Net investment income	638,692	460,864	1,724,005	1,203,389
Asset administration fees:
Direct	83,659	81,422	246,123	242,730
Assumed	0	0	0	0
Ceded	(27,231)	(24,668)	(77,950)	(64,986)
Net asset administration fees	56,428	56,754	168,173	177,744
Other income (loss):
Direct	332,233	(89,144)	461,980	216,247
Assumed	(75)	116	274	(233)
Ceded	53,937	25,473	275,015	70,736
Net other income (loss)	386,095	(63,555)	737,269	286,750
Realized investment gains (losses), net:
Direct	(541,864)	(492,184)	235,638	(826,822)
Assumed	14,552	(31,544)	77,736	189,400
Ceded	(89,183)	55,472	(67,987)	56,181
Realized investment gains (losses), net	(616,495)	(468,256)	245,387	(581,241)
Change in value of market risk benefits, net of related hedging gain (loss):
Direct	(214,414)	(54,544)	(199,087)	152,660
Assumed	(245)	283	361	(3,160)
Ceded	39,258	(193,210)	(167,267)	(415,656)
Net change in value of market risk benefits, net of related hedging gain (loss)	(175,401)	(247,471)	(365,993)	(266,156)
Policyholders’ benefits (including change in reserves):
Direct	855,117	912,588	2,765,937	2,639,868
Assumed	242,113	336,300	775,334	985,635
Ceded	(966,549)	(1,103,479)	831,697	(3,227,951)
Net policyholders’ benefits (including change in reserves	130,681	145,409	4,372,968	397,552
Change in estimates of liability for future policy benefits:
Direct	142,204	(44,155)	354,660	(61,510)
Assumed	17,025	(17,580)	81,893	8,071
Ceded	(156,795)	68,300	(452,298)	54,469
Change in estimates of liability for future policy benefits	2,434	6,565	(15,745)	1,030
Interest credited to policyholders’ account balances:
Direct	332,064	228,399	907,648	666,947
Assumed	35,476	33,602	117,968	100,065
Ceded	(111,380)	(98,927)	(318,682)	(299,900)
Net interest credited to policyholders’ account balances	256,160	163,074	706,934	467,112
Reinsurance expense allowances and general and administrative expenses, net of capitalization and amortization	(113,741)	(57,368)	(619,914)	(280,393)
Unaffiliated activity
Premiums:
Assumed	29	32	89	(100)
Ceded	(27,821)	(13,942)	(79,800)	(47,319)
Policy charges and fee income:
Assumed	429	460	1,057	1,383
Ceded	(45,692)	(39,143)	(132,662)	(101,419)
Net investment income:
Ceded	0	10,109	0	23,022
Asset administration fees:
Ceded	(7,151)	(7,464)	(21,474)	(15,204)
Other income (loss):
Assumed	(75)	185	378	(53)
Ceded	26,125	7,887	73,931	17,540
Realized investment gains (losses), net:
Assumed	14,552	(31,544)	77,736	189,400
Ceded	(76,021)	41,007	(29,022)	40,378
Change in value of market risk benefits, net of related hedging gain (loss):
Assumed	(245)	283	361	(3,160)
Ceded	5,318	(70,693)	(58,229)	(150,791)
Policyholders’ benefits (including change in reserves):
Assumed	(145)
Assumed		265	216	545
Ceded	(51,927)	(42,655)	(262,998)	(106,475)
Change in estimates of liability for future policy benefits:
Ceded	673	(1,407)	92,575	(1,823)
Interest credited to policyholders’ account balances:
Assumed	6,772	3,651	31,888	8,750
Ceded	$ 1	$ 85	$ 0	$ 0