Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Unrealized gains (losses) for assets/liabilities still held:
Market risk benefit assets	$ 2,508,967	$ 2,537,000	$ 2,637,363
Market risk benefit liabilities	4,803,284	4,388,000	$ 4,281,244
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	20,515	28,709
Purchases	0	273
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	20,274	28,650
Total gains (losses) (realized/unrealized):
Included in earnings	(241)	(332)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(241)	(332)
Equity securities | 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
Equity securities | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	(241)	(332)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(241)	(332)
Equity securities | 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
Equity securities | 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
Equity securities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Other invested assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	143	1
Purchases	0	(1)
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	32	1
Total gains (losses) (realized/unrealized):
Included in earnings	(111)	1
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(111)	1
Other invested assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(111)	1
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(111)	1
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	105,540	1,759
Purchases	2,500	2,002
Sales	(1,524)	0
Issuances	0	0
Settlements	(34)	(94)
Other	(1,398)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	104,761	3,351
Total gains (losses) (realized/unrealized):
Included in earnings	(323)	(316)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(323)	(316)
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	28	(316)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	28	(316)
Short-term investments | 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
Short-term investments | 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
Short-term investments | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	(351)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(351)	0
Short-term investments | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Cash equivalents
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	33
Purchases	206
Sales	0
Issuances	0
Settlements	(16)
Other	(33)
Transfers into Level 3	0
Transfers out of Level 3	0
Fair Value, end of period	103
Total gains (losses) (realized/unrealized):
Included in earnings	(87)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(87)
Cash equivalents | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(87)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(87)
Cash equivalents | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0
Cash equivalents | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0
Cash equivalents | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0
Cash equivalents | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0
Receivables from parents and affiliates
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	351,390	0
Purchases	55,295	121,378
Sales	(9,253)	0
Issuances	0	0
Settlements	(2,789)	0
Other	5,867	0
Transfers into Level 3	0	0
Transfers out of Level 3	(18,098)	0
Fair Value, end of period	379,360	121,378
Total gains (losses) (realized/unrealized):
Included in earnings	(3,052)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(3,093)	0
Receivables from parents and affiliates | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(4,071)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(3,899)
Receivables from parents and affiliates | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0
Receivables from parents and affiliates | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0
Receivables from parents and affiliates | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	1,019
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	806
Receivables from parents and affiliates | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0
Reinsurance recoverables and deposit receivables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	645,193	192,642
Purchases	72,293	72,576
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	716,745	250,878
Total gains (losses) (realized/unrealized):
Included in earnings	(741)	(14,340)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	41,155	(51,458)
Reinsurance recoverables and deposit receivables | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(741)	(14,340)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	41,155	(51,458)
Reinsurance recoverables and deposit receivables | 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
Reinsurance recoverables and deposit receivables | 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
Reinsurance recoverables and deposit receivables | 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
Reinsurance recoverables and deposit receivables | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Separate account assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	10,547	5,985
Purchases	1,876	2,633
Sales	(69)	(1,256)
Issuances	0	0
Settlements	(11)	(125)
Other	0	0
Transfers into Level 3	0	458
Transfers out of Level 3	0	0
Fair Value, end of period	12,242	7,894
Total gains (losses) (realized/unrealized):
Included in earnings	(101)	199
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(101)	200
Separate account assets | 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
Separate account 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
Separate account assets | Interest credited to policyholders’ account balances
Total gains (losses) (realized/unrealized):
Included in earnings	(101)	199
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(101)	200
Separate account 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
Separate account assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Policyholders' account balances
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(12,624,585)	(7,697,627)
Purchases	0	0
Sales	0	0
Issuances	(627,295)	(560,400)
Settlements	0	0
Other	0	813
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(11,817,734)	(9,752,538)
Total gains (losses) (realized/unrealized):
Included in earnings	1,434,146	(1,495,324)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	403,703	(134,807)
Policyholders' account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	1,434,146	(1,495,324)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	403,703	(134,807)
Policyholders' account balances | 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
Policyholders' account balances | 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
Policyholders' account balances | 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
Policyholders' account balances | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Other liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(31)	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	(12,504)	(207)
Total gains (losses) (realized/unrealized):
Included in earnings	(12,473)	(207)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(12,473)	(207)
Other liabilities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(12,473)	(207)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(12,473)	(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	(6,667)	(1,696)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(6,178)	626
Available-for-sale | Fixed maturities | 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
Available-for-sale | Fixed maturities | 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
Available-for-sale | Fixed maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	8,780	(9,842)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	8,900	(10,521)
Available-for-sale | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	(942)	598
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	648	682
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(640)	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	0	671
Total gains (losses) (realized/unrealized):
Included in earnings	(8)	(11)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(13)
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	1,199,607	1,014,343
Purchases	416,528	125,041
Sales	(159,562)	(65,052)
Issuances	0	0
Settlements	(40,372)	(53,892)
Other	(4,435)	0
Transfers into Level 3	31,000	0
Transfers out of Level 3	0	0
Fair Value, end of period	1,441,168	1,009,650
Total gains (losses) (realized/unrealized):
Included in earnings	(1,598)	(10,790)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(759)	(9,602)
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	699,892	177,237
Purchases	321,883	484,340
Sales	(203,502)	0
Issuances	0	0
Settlements	(36,655)	(1,895)
Other	(58,357)	0
Transfers into Level 3	261,816	34,578
Transfers out of Level 3	(56,500)	0
Fair Value, end of period	931,354	694,121
Total gains (losses) (realized/unrealized):
Included in earnings	2,777	(139)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	3,481	(280)
Trading | Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	66,285	34,048
Purchases	82,403	113,343
Sales	0	0
Issuances	0	0
Settlements	(26,130)	0
Other	58,357	0
Transfers into Level 3	2,001	0
Transfers out of Level 3	(34,428)	0
Fair Value, end of period	152,081	146,543
Total gains (losses) (realized/unrealized):
Included in earnings	3,593	(848)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	6,190	(848)
Trading | Fixed maturities | 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
Trading | Fixed maturities | Other income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	6,190	(848)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	6,190	(848)
Trading | Fixed maturities | 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
Trading | Fixed maturities | 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
Trading | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	$ (2,597)	$ 0