Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Unrealized gains (losses) for assets/liabilities still held:
Market risk benefits assets	$ 2,550,164	$ 2,340,000	$ 2,550,164	$ 2,340,000	$ 2,367,243
Market risk benefit liabilities	4,370,960	5,090,000	4,370,960	5,090,000	$ 5,144,401
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	28,650	43,174	28,709	28,593
Purchases	0	0	273	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Other	0	181	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	28,330	43,374	28,330	43,374
Total gains (losses) (realized/unrealized):
Included in earnings	(320)	19	(652)	(811)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(320)	19	(652)	(811)
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	(320)	19	(652)	(811)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(320)	19	(652)	(811)
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	1		1
Purchases	1		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	763		763
Total gains (losses) (realized/unrealized):
Included in earnings	761		762
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	761		762
Other invested assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	761		762
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	761		762
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	3,351	14,416	1,759	16,945
Purchases	304	1,146	2,306	2,688
Sales	(8)	0	(8)	0
Issuances	0	0	0	0
Settlements	(1,293)	(13,711)	(1,387)	(19,638)
Other	0	(1,359)	0	(1,359)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	2,674	1,209	2,674	1,209
Total gains (losses) (realized/unrealized):
Included in earnings	320	717	4	2,573
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	308	0	(8)	51
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	308	423	(8)	1,857
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	308	0	(8)	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	(124)	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	12	418	12	789
Cash equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0		0
Purchases	605		605
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	605		605
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	303,538	155,763	224,019	141,041
Purchases	58,326	38,983	114,032	73,603
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(12,842)	(3,514)	(26,036)	(5,051)
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	363,440	217,613	363,440	217,613
Total gains (losses) (realized/unrealized):
Included in earnings	14,418	26,381	51,425	8,020
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1,575	19,779	25,388	2,969
Other assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	14,418	26,381	51,425	8,020
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	1,575	19,779	25,388	2,969
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	121,378	0	0	0
Purchases	111,140	0	232,518	0
Sales	(51,199)	0	(51,199)	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	181,319	0	181,319	0
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 | 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
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	0	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0	0
Receivables from parents and affiliates | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0	0
Reinsurance Recoverables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	96,442	1,357	69,745	0
Purchases	51,033	0	83,251	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	127,289	1,465	127,289	1,465
Total gains (losses) (realized/unrealized):
Included in earnings	(20,186)	108	(25,707)	1,465
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(43,624)	108	(78,715)	1,465
Reinsurance Recoverables | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(20,186)	108	(25,707)	1,465
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(43,624)	108	(78,715)	1,465
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	7,894	4,553	5,985	4,645
Purchases	1,805	840	4,438	840
Sales	(2)	(420)	(1,258)	(600)
Issuances	0	0	0	0
Settlements	0	(150)	(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	9,799	4,982	9,799	4,982
Total gains (losses) (realized/unrealized):
Included in earnings	102	159	301	257
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	102	159	302	255
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	102	159	301	257
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	102	159	302	255
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	(9,752,538)	(4,129,043)	(7,689,929)	(3,502,096)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	(545,676)	(439,615)	(1,106,074)	(838,238)
Settlements	0	0	0	0
Other	1,117	72,773	1,930	74,368
Transfers Into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	(10,083,258)	(5,513,449)	(10,083,258)	(5,513,449)
Total gains (losses) (realized/unrealized):
Included in earnings	213,839	(1,017,564)	(1,289,185)	(1,247,483)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	973,682	(150,676)	831,176	(234,970)
Policyholders' account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	213,839	(1,017,564)	(1,289,185)	(1,247,483)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	973,682	(150,676)	831,176	(234,970)
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	(207)		(207)
Total gains (losses) (realized/unrealized):
Included in earnings	0		(207)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		(207)
Other liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0		(207)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0		(207)
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	(2,567)	(1,138)	(4,263)	(813)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,404)	(1,118)	(776)	(2,019)
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	(4,746)	3,476	(14,588)	4,440
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(5,304)	3,359	(15,825)	5,275
Available-for-sale | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	924	(39)	1,522	350
Available-for-sale | Fixed maturities | Foreign government bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	671	714	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	664	701	664	701
Total gains (losses) (realized/unrealized):
Included in earnings	(7)	(13)	(18)	(23)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(11)	(16)	(24)	(28)
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	1,009,650	535,893	1,014,343	507,496
Purchases	203,749	216,778	328,790	310,874
Sales	(65,650)	(9,241)	(130,702)	(28,839)
Issuances	0	0	0	0
Settlements	(71,908)	(25,418)	(125,800)	(76,842)
Other	(65,480)	1,359	(65,480)	1,359
Transfers into Level 3	942	0	942	0
Transfers out of Level 3	0	0	0	0
Fair Value, end of period	1,005,175	721,247	1,005,175	721,247
Total gains (losses) (realized/unrealized):
Included in earnings	(6,128)	1,876	(16,918)	7,199
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(7,077)	1,773	(16,678)	6,413
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	694,121	228,869	177,237	104,724
Purchases	37,188	1,291	521,528	147,307
Sales	0	0	0	(27)
Issuances	0	0	0	0
Settlements	(51,300)	(725)	(53,195)	(1,338)
Other	65,480	0	65,480	0
Transfers into Level 3	0	0	34,578	2,240
Transfers out of Level 3	(77,200)	(83,532)	(77,200)	(103,368)
Fair Value, end of period	668,035	146,339	668,035	146,339
Total gains (losses) (realized/unrealized):
Included in earnings	(254)	436	(393)	(3,199)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	380	484	101	(3,129)
Trading | Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	146,543	6,250	34,048	0
Purchases	111,784	0	225,127	6,250
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(2,261)	0	(2,261)	0
Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(15,196)	(6,250)	(15,196)	(6,250)
Fair Value, end of period	240,820	0	240,820	0
Total gains (losses) (realized/unrealized):
Included in earnings	(50)	0	(898)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(42)	0	(890)	0
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	(50)	0	(898)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(42)	0	(890)	0
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	$ 0	$ 0	$ 0	$ 0