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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Unrealized gains (losses) for assets/liabilities still held:
Market risk benefits assets	$ 2,499,234	$ 2,519,000	$ 2,499,234	$ 2,519,000	$ 2,367,243
Market risk benefit liabilities	4,915,163	4,371,000	4,915,163	4,371,000	$ 5,144,401
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	28,330	43,374	28,709	28,593
Purchases	0	2,531	273	2,531
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	0	0	15,592
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	29,240	44,686	29,240	44,686
Total gains (losses) (realized/unrealized):
Included in earnings	910	(1,219)	258	(2,030)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	910	(1,219)	258	(2,030)
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	910	(1,219)	258	(2,030)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	910	(1,219)	258	(2,030)
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	763		1
Purchases	0		0
Sales	0		0
Issuances	0		0
Settlements	0		0
Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	794		794
Total gains (losses) (realized/unrealized):
Included in earnings	31		793
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	31		793
Other invested assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	31		793
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	31		793
Other invested assets | 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
Other invested assets | 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
Other invested assets | 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
Other invested assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Short-term investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	2,674	1,209	1,759	16,945
Purchases	102,151	802	104,457	3,490
Sales	0	0	(8)	0
Issuances	0	0	0	0
Settlements	(62)	(1,427)	(1,449)	(21,065)
Other	476	0	476	(1,359)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	105,198	584	105,198	584
Total gains (losses) (realized/unrealized):
Included in earnings	(41)	0	(37)	2,573
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(41)	0	(49)	51
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(41)	0	(49)	1,857
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(41)	0	(49)	0
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	0	(73)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	51
Short-term investments | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	12	789
Cash equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	605		0
Purchases	2		607
Sales	0		0
Issuances	0		0
Settlements	0		0
Other	(489)		(489)
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	118		118
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		0
Cash equivalents | 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
Cash equivalents | 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
Cash equivalents | 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
Cash equivalents | 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
Cash equivalents | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	363,440	217,613	224,019	141,041
Purchases	62,471	33,850	176,503	107,453
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(14,009)	(6,512)	(40,045)	(11,563)
Other	88,047	0	88,047	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	509,723	270,490	509,723	270,490
Total gains (losses) (realized/unrealized):
Included in earnings	9,774	25,539	61,199	33,559
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(4,234)	19,028	21,154	21,997
Other assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	9,774	25,539	61,199	33,559
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(4,234)	19,028	21,154	21,997
Other 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 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 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 assets | 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	181,319		0
Purchases	157,703		390,221
Sales	0		(51,199)
Issuances	0		0
Settlements	0		0
Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	339,041		339,041
Total gains (losses) (realized/unrealized):
Included in earnings	19		19
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	19		19
Receivables from parents and affiliates | 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
Receivables from parents and affiliates | 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
Receivables from parents and affiliates | 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
Receivables from parents and affiliates | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	19		19
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	19		19
Receivables from parents and affiliates | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0		0
Reinsurance Recoverables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	127,289	1,465	69,745	0
Purchases	51,231	0	134,482	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	5,183	0	5,183	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	201,559	15,544	201,559	15,544
Total gains (losses) (realized/unrealized):
Included in earnings	17,856	14,079	(7,851)	15,544
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(26,796)	14,079	(105,511)	15,544
Reinsurance Recoverables | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	17,856	14,079	(7,851)	15,544
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(26,796)	14,079	(105,511)	15,544
Reinsurance Recoverables | 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 | 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 | 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 | 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	9,799	4,982	5,985	4,645
Purchases	820	1,049	5,258	1,889
Sales	(732)	(524)	(1,990)	(1,124)
Issuances	0	0	0	0
Settlements	0	0	(125)	(160)
Other	0	0	0	0
Transfers into Level 3	0	0	458	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	10,117	5,500	10,117	5,500
Total gains (losses) (realized/unrealized):
Included in earnings	230	(7)	531	250
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	231	(6)	533	249
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	230	(7)	531	250
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	231	(6)	533	249
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	(10,083,258)	(5,513,449)	(7,689,929)	(3,502,096)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(718,242)	(413,219)	(1,824,316)	(1,251,457)
Settlements	0	0	0	0
Other	44,999	28,467	46,929	102,835
Transfers Into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(11,854,608)	(6,005,729)	(11,854,608)	(6,005,729)
Total gains (losses) (realized/unrealized):
Included in earnings	(1,098,107)	(107,528)	(2,387,292)	(1,355,011)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	269,505	(273,135)	1,100,681	(508,105)
Policyholders' account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(1,098,107)	(107,528)	(2,387,292)	(1,355,011)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	269,505	(273,135)	1,100,681	(508,105)
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	(207)		0
Purchases	0		0
Sales	0		0
Issuances	0		0
Settlements	0		0
Other	0		0
Transfers Into Level 3	0		0
Transfers out of Level 3	0		0
Fair Value, end of period	(693)		(693)
Total gains (losses) (realized/unrealized):
Included in earnings	(486)		(693)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(486)		(693)
Other liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(486)		(693)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(486)		(693)
Other liabilities | 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
Other liabilities | 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
Other liabilities | 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
Other liabilities | 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	(15,515)	(1,048)	(19,778)	(1,861)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(12,047)	(674)	(12,822)	(2,693)
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	17,745	(31,183)	3,157	(26,743)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	17,374	(31,435)	1,549	(26,160)
Available-for-sale | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	(783)	507	739	857
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	664	701	682	724
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	657	686	657	686
Total gains (losses) (realized/unrealized):
Included in earnings	(7)	(15)	(25)	(38)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(9)	(17)	(32)	(46)
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	1,005,175	721,247	1,014,343	507,496
Purchases	540,137	182,465	868,927	493,339
Sales	(223,172)	(10,882)	(353,874)	(39,721)
Issuances	0	0	0	0
Settlements	(28,144)	(27,762)	(153,944)	(104,604)
Other	12	(708)	(65,468)	651
Transfers into Level 3	31,385	117,152	32,327	117,152
Transfers out of Level 3	0	(9,088)	0	(9,088)
Fair Value, end of period	1,320,615	944,586	1,320,615	944,586
Total gains (losses) (realized/unrealized):
Included in earnings	(4,778)	(27,838)	(21,696)	(20,639)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,374)	(28,256)	(18,051)	(21,842)
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	668,035	146,339	177,237	104,724
Purchases	40,941	53,352	562,469	200,659
Sales	0	0	0	(27)
Issuances	0	0	0	0
Settlements	(20,113)	(339)	(73,308)	(1,677)
Other	0	0	65,480	0
Transfers into Level 3	0	2,297	34,578	4,537
Transfers out of Level 3	(3,999)	(7,600)	(81,199)	(110,968)
Fair Value, end of period	691,096	190,178	691,096	190,178
Total gains (losses) (realized/unrealized):
Included in earnings	6,232	(3,871)	5,839	(7,070)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	6,710	(3,836)	6,810	(6,965)
Trading | Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	240,820	0	34,048	0
Purchases	7,252	0	232,379	6,250
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	(2,261)	0
Other	0	707	0	707
Transfers into Level 3	18,842	0	18,842	0
Transfers out of Level 3	(214,209)	0	(229,405)	(6,250)
Fair Value, end of period	52,863	725	52,863	725
Total gains (losses) (realized/unrealized):
Included in earnings	158	18	(740)	18
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	184	18	(706)	18
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	183	18	(715)	18
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	184	18	(706)	18
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	$ (25)	$ 0	$ (25)	$ 0