Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	$ 7,889	$ 9,898
Purchases	0	0
Sales	0	(4,830)
Issuances	0	0
Settlements	0	0
Other	3,874	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	12,472	7,889	$ 9,898
Total gains (losses) (realized/unrealized):
Included in earnings	709	2,821
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	709	1,211
Equity securities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Equity securities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	709	2,821	1,668
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	709	1,211	1,534
Equity securities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	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	0
Other invested assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	4
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	0	0	4
Total gains (losses) (realized/unrealized):
Included in earnings	0	(4)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(4)
Other invested assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	(4)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	(4)	0
Other invested assets | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Other invested assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	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	0
Short-term investments
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	0	0
Settlements	(1,871)	0
Other	1,690	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	0	0	0
Total gains (losses) (realized/unrealized):
Included in earnings	181	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Short-term investments | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	181	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Short-term investments | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Short-term investments | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Short-term investments | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Cash equivalents
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	0	0
Settlements	(1,377)	0
Other	1,230	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	0	0	0
Total gains (losses) (realized/unrealized):
Included in earnings	147	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	147	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Cash equivalents | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Cash equivalents | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	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	0
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	0
Purchases	1,170	0
Sales	0	0
Issuances	0	0
Settlements	(899)	0
Other	71,408	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	72,937	0	0
Total gains (losses) (realized/unrealized):
Included in earnings	1,258	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	359	0
Other assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	1,258	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	359	0	0
Other assets | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Other assets | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Other assets | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Reinsurance recoverables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	13,239,539	8,539,671
Purchases	629,259	1,095,793
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	931,207	13,239,539	8,539,671
Total gains (losses) (realized/unrealized):
Included in earnings	(12,937,591)	3,604,075
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(545,001)	3,889,923
Reinsurance recoverables | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(12,937,591)	3,604,075	1,936,363
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(545,001)	3,889,923	2,142,421
Reinsurance recoverables | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Reinsurance recoverables | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Reinsurance recoverables | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Receivables from parent and affiliates
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	3,135
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	(3,158)
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	0	0	3,135
Total gains (losses) (realized/unrealized):
Included in earnings	0	23
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Receivables from parent and affiliates | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Receivables from parent and affiliates | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Receivables from parent and affiliates | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Receivables from parent and affiliates | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	23	190
Future policy benefits
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(13,227,814)	(8,529,566)
Purchases	0	0
Sales	0	0
Issuances	(1,101,695)	(1,087,967)
Settlements	0	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(9,047,956)	(13,227,814)	(8,529,566)
Total gains (losses) (realized/unrealized):
Included in earnings	5,281,553	(3,610,281)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	4,647,753	(3,896,128)
Future policy benefits | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	5,281,553	(3,610,281)	(1,945,323)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	4,647,753	(3,896,128)	(2,151,380)
Future policy benefits | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Future policy benefits | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Future policy benefits | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Policyholders' account balances
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(1,155,274)	(962,351)
Purchases	0	0
Sales	0	0
Issuances	(265,807)	(162,724)
Settlements	0	0
Other	(1,746,371)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(3,245,773)	(1,155,274)	(962,351)
Total gains (losses) (realized/unrealized):
Included in earnings	(78,321)	(30,199)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	5,476	3,853
Policyholders' account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(78,321)	(30,199)	(765,917)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	5,476	3,853	(759,661)
Policyholders' account balances | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Policyholders' account balances | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	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	0
Available-for-sale | Fixed maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(832)	(5,019)	(8,198)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,778)	(4,773)	(8,467)
Available-for-sale | Fixed maturities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Available-for-sale | Fixed maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	(6,318)	19,106	3,615
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(5,346)	18,962
Available-for-sale | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	388	145	680
Available-for-sale | Fixed maturities | US government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	55,000	38,671
Purchases	0	16,329
Sales	(55,000)	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	0	55,000	38,671
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 | Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	163	163
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	150	163	163
Total gains (losses) (realized/unrealized):
Included in earnings	(13)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(15)	(1)
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	174,776	50,083
Purchases	95,294	11,121
Sales	(5,085)	(3,680)
Issuances	0	0
Settlements	(28,690)	(7,850)
Other	156,667	(1,914)
Transfers into Level 3	9,313	114,695
Transfers out of Level 3	(5,727)	(2,394)
Fair Value, end of period	385,634	174,776	50,083
Total gains (losses) (realized/unrealized):
Included in earnings	(10,914)	14,715
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(11,298)	14,679
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	2,065	2,001
Purchases	74,800	7,444
Sales	(29)	(6)
Issuances	0	0
Settlements	(1,761)	(1,255)
Other	32,859	0
Transfers into Level 3	107,038	0
Transfers out of Level 3	(45,193)	(5,636)
Fair Value, end of period	173,944	2,065	2,001
Total gains (losses) (realized/unrealized):
Included in earnings	4,165	(483)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	4,189	(489)
Trading | Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	755	668
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	801	0
Fair Value, end of period	0	755	668
Total gains (losses) (realized/unrealized):
Included in earnings	46	87
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	46	87
Trading | Fixed maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	0	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0	0
Trading | Fixed maturities | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	46	87	(83)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	46	87	(83)
Trading | Fixed maturities | Included in other comprehensive income (loss)
Total gains (losses) (realized/unrealized):
Included in earnings	0	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	$ 0	$ 0	$ 0