Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	$ 12,472	$ 7,889
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	11,463	7,678
Total gains (losses) (realized/unrealized):
Included in earnings	(1,009)	(211)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,009)	(211)
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
Total gains (losses) (realized/unrealized):
Included in earnings	(1,009)	(211)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,009)	(211)
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 assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	72,937	0
Purchases	7,816	0
Sales	0	0
Issuances	0	0
Settlements	(1,838)	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	75,201	0
Total gains (losses) (realized/unrealized):
Included in earnings	(3,714)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,877)	0
Other assets | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(3,714)	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(1,877)	0
Other assets | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Other 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 assets | 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	931,207	13,239,539
Purchases	35,301	278,233
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	700,700	7,447,863
Total gains (losses) (realized/unrealized):
Included in earnings	(265,808)	(6,069,909)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(257,911)	(5,914,192)
Reinsurance recoverables | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(265,808)	(6,069,909)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(257,911)	(5,914,192)
Reinsurance recoverables | Other income
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 | 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 | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Future policy benefits
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	(9,047,956)	(13,227,814)
Purchases	0	0
Sales	0	0
Issuances	(263,018)	(276,249)
Settlements	0	0
Other	0	0
Transfers Into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(6,964,587)	(7,435,081)
Total gains (losses) (realized/unrealized):
Included in earnings	2,346,387	6,068,982
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	2,259,260	5,913,265
Future policy benefits | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	2,346,387	6,068,982
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	2,259,260	5,913,265
Future policy benefits | Other income
Total gains (losses) (realized/unrealized):
Included in earnings	0	0
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	0
Future policy benefits | 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
Future policy benefits | 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	(3,245,773)	(1,155,274)
Purchases	0	0
Sales	0	0
Issuances	(152,791)	0
Settlements	0	13,492
Other	239,022	0
Transfers Into Level 3	0	0
Transfers out of Level 3	0	0
Fair Value, end of period	(3,260,195)	(1,031,525)
Total gains (losses) (realized/unrealized):
Included in earnings	(100,653)	110,257
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(70,214)	128,490
Policyholders' account balances | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(100,653)	110,257
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(70,214)	128,490
Policyholders' account balances | Other income
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
Available-for-sale | Fixed maturities | Realized investment gains (losses), net
Total gains (losses) (realized/unrealized):
Included in earnings	(14,903)	(508)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(15,011)	(500)
Available-for-sale | Fixed maturities | Other income
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	(33,841)	(11,618)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(33,439)	(11,621)
Available-for-sale | Fixed maturities | Net investment income
Total gains (losses) (realized/unrealized):
Included in earnings	383	23
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	0	55,000
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	55,000
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 bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	150	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	140	157
Total gains (losses) (realized/unrealized):
Included in earnings	(10)	(6)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(10)	(6)
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	385,634	174,776
Purchases	49,410	2,319
Sales	(1,171)	0
Issuances	0	0
Settlements	(12,140)	(2,165)
Other	0	0
Transfers into Level 3	0	2,643
Transfers out of Level 3	0	0
Fair Value, end of period	385,358	165,491
Total gains (losses) (realized/unrealized):
Included in earnings	(36,375)	(12,082)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(36,465)	(12,101)
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	173,944	2,065
Purchases	0	500
Sales	0	0
Issuances	0	0
Settlements	(502)	(416)
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(49,350)	0
Fair Value, end of period	112,116	2,134
Total gains (losses) (realized/unrealized):
Included in earnings	(11,976)	(15)
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	(11,975)	(14)
Trading | Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period	0	755
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	767
Total gains (losses) (realized/unrealized):
Included in earnings	0	12
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	12
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
Total gains (losses) (realized/unrealized):
Included in earnings	0	12
Unrealized gains (losses) for assets/liabilities still held:
Included in earnings	0	12
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	$ 0	$ 0