Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Unrealized gains (losses) for assets/liabilities still held:
Market risk benefit assets	$ 2,584,710	$ 2,499,234	$ 2,584,710	$ 2,499,234	$ 2,637,363
Market risk benefit liabilities	4,618,333	4,915,163	4,618,333	4,915,163	$ 4,281,244
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	2,173	28,330	20,515	28,709
Purchases	75	0	2,248	273
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	(20,274)	0
Fair Value, end of period	2,173	29,240	2,173	29,240
Total gains (losses) (realized/unrealized):
Included in earnings	(75)	910	(316)	258
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(75)	910	(316)	258
Equity securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Equity securities | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	(75)	910	(316)	258
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(75)	910	(316)	258
Equity securities | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Equity securities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Equity securities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Other invested assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	50	763	143	1
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	0	794	0	794
Total gains (losses) (realized/unrealized):
Included in earnings	(50)	31	(143)	793
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(50)	31	(143)	793
Other invested assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(50)	31	(143)	793
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(50)	31	(143)	793
Other invested assets | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other invested assets | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other invested assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other invested assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Short-term investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	795	2,674	105,540	1,759
Purchases	799	102,151	3,628	104,457
Sales	(390)	0	(103,914)	(8)
Issuances	0	0	0	0
Settlements	(420)	(62)	(2,840)	(1,449)
Other	185	476	(1,213)	476
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	979	105,198	979	105,198
Total gains (losses) (realized/unrealized):
Included in earnings	10	(41)	(222)	(37)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	10	(41)	(320)	(49)
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	10	(41)	163	(49)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	10	(41)	31	(49)
Short-term investments | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Short-term investments | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Short-term investments | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	(385)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	(351)	0
Short-term investments | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	12
Cash equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	278	605	33	0
Purchases	41	2	593	607
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(15)	0	(239)	0
Other	(274)	(489)	(307)	(489)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	30	118	30	118
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	(50)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	(80)	0
Cash equivalents | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	(50)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	(80)	0
Cash equivalents | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Cash equivalents | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Cash equivalents | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Cash equivalents | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Receivables from parents and affiliates
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	366,535	181,319	351,390	0
Purchases	11,993	157,703	72,696	390,221
Sales	(1,285)	0	(14,057)	(51,199)
Issuances	0	0	0	0
Settlements	(115,384)	0	(135,111)	0
Other	0	0	5,867	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	(18,098)	0
Fair Value, end of period	261,435	339,041	261,435	339,041
Total gains (losses) (realized/unrealized):
Included in earnings	(424)	19	(1,252)	19
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(424)	19	1,189	19
Receivables from parents and affiliates | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(1)	0	(2,248)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Receivables from parents and affiliates | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Receivables from parents and affiliates | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Receivables from parents and affiliates | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	(422)	19	999	19
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(424)	19	1,189	19
Receivables from parents and affiliates | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	(1)	0	(3)	0
Reinsurance recoverables and deposit receivables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	722,068	309,681	645,193	192,642
Purchases	70,017	93,275	136,289	256,660
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	93,230	0	93,230
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	753,654	492,719	753,654	492,719
Total gains (losses) (realized/unrealized):
Included in earnings	(38,431)	(3,467)	(27,828)	(49,813)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(186,921)	(56,106)	(285,247)	(170,068)
Reinsurance recoverables and deposit receivables | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(38,431)	(3,467)	(27,828)	(49,813)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(186,921)	(56,106)	(285,247)	(170,068)
Reinsurance recoverables and deposit receivables | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Reinsurance recoverables and deposit receivables | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Reinsurance recoverables and deposit receivables | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Reinsurance recoverables and deposit receivables | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Separate account assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	13,322	9,799	10,547	5,985
Purchases	3,303	820	6,447	5,258
Sales	(168)	(732)	(770)	(1,990)
Issuances	0	0	0	0
Settlements	(28)	0	(68)	(125)
Other	0	0	0	0
Transfers into Level 3	0	0	0	458
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	16,736	10,117	16,736	10,117
Total gains (losses) (realized/unrealized):
Included in earnings	307	230	580	531
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	307	231	580	533
Separate account assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Separate account assets | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Separate account assets | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	307	230	580	531
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	307	231	580	533
Separate account assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Separate account assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Policyholders' account balances
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(15,113,285)	(10,083,258)	(12,624,585)	(7,697,627)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(383,704)	(718,242)	(1,228,402)	(1,824,318)
Settlements	0	0	0	0
Other	0	44,999	0	46,929
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(17,778,505)	(11,854,608)	(17,778,505)	(11,854,608)
Total gains (losses) (realized/unrealized):
Included in earnings	(2,281,516)	(1,098,107)	(3,925,518)	(2,379,592)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	161,641	269,505	294,335	1,108,381
Policyholders' account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(2,281,516)	(1,098,107)	(3,925,518)	(2,379,592)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	161,641	269,505	294,335	1,108,381
Policyholders' account balances | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Policyholders' account balances | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Policyholders' account balances | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Policyholders' account balances | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Other liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(14,303)	(207)	(31)	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	0	(693)	0	(693)
Total gains (losses) (realized/unrealized):
Included in earnings	14,303	(486)	31	(693)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	14,303	(486)	31	(693)
Other liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	14,303	(486)	31	(693)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	14,303	(486)	31	(693)
Other liabilities | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other liabilities | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other liabilities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Other liabilities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Notes issued by consolidated VIEs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0		0
Purchases	0		0
Sales	0		0
Issuances	(17,538)		(17,538)
Settlements	0		0
Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	(17,538)		(17,538)
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Notes issued by consolidated VIEs | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Notes issued by consolidated VIEs | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Notes issued by consolidated VIEs | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Notes issued by consolidated VIEs | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Notes issued by consolidated VIEs | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Available-for-sale | Fixed maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(22,269)	(15,515)	(29,724)	(19,778)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(26,531)	(12,047)	(34,774)	(12,822)
Available-for-sale | Fixed maturities | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Available-for-sale | Fixed maturities | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Available-for-sale | Fixed maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	8,544	17,745	39,671	3,157
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	8,199	17,374	37,226	1,549
Available-for-sale | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	502	(783)	(844)	739
Available-for-sale | Fixed maturities | Foreign government securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	664	648	682
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	(640)	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	0	657	0	657
Total gains (losses) (realized/unrealized):
Included in earnings	0	(7)	(8)	(25)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(9)	0	(32)
Available-for-sale | Fixed maturities | Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1,257,603	1,005,175	1,199,607	1,014,343
Purchases	68,548	540,137	805,335	868,927
Sales	(53,603)	(223,172)	(612,971)	(353,874)
Issuances	0	0	0	0
Settlements	(57,522)	(28,144)	(227,318)	(153,944)
Other	88	12	(4,347)	(65,468)
Transfers into Level 3	0	31,385	33,612	32,327
Transfers out of Level 3	(14,610)	0	(14,610)	0
Fair Value, end of period	1,183,318	1,320,615	1,183,318	1,320,615
Total gains (losses) (realized/unrealized):
Included in earnings	(17,186)	(4,778)	4,010	(21,696)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(22,654)	(1,374)	(3,778)	(18,051)
Available-for-sale | Fixed maturities | Structured securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	1,190,303	668,035	699,892	177,237
Purchases	162,145	40,941	636,679	562,469
Sales	0	0	(38,215)	0
Issuances	0	0	0	0
Settlements	(40,938)	(20,113)	(129,781)	(73,308)
Other	0	0	(28,544)	65,480
Transfers into Level 3	14,698	0	283,514	34,578
Transfers out of Level 3	(87,100)	(3,999)	(185,575)	(81,199)
Fair Value, end of period	1,243,071	691,096	1,243,071	691,096
Total gains (losses) (realized/unrealized):
Included in earnings	3,963	6,232	5,101	5,839
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	4,322	6,710	6,230	6,810
Trading | Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	222,095	240,820	66,285	34,048
Purchases	223,879	7,252	433,650	232,379
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	(26,130)	(2,261)
Other	0	0	28,544	0
Transfers into Level 3	1	18,842	2,002	18,842
Transfers out of Level 3	1	(214,209)	(76,934)	(229,405)
Fair Value, end of period	449,824	52,863	449,824	52,863
Total gains (losses) (realized/unrealized):
Included in earnings	3,848	158	22,407	(740)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	4,280	184	25,598	(706)
Trading | Fixed maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading | Fixed maturities | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	4,279	183	22,986	(715)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	4,280	184	25,598	(706)
Trading | Fixed maturities | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading | Fixed maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Trading | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	$ (431)	$ (25)	$ (579)	$ (25)