Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Policy loans	$ 1,327,485	$ 1,323,681
Short-term Investments	182,437
Cash and cash equivalents	918,931	426,979	$ 563,199	$ 416,840
Accrued investment income	160,027	93,613
Reinsurance recoverables	38,598,767	48,367,096
Receivables from parent and affiliates	278,131	266,473
Liabilities:
Cash collateral for loaned securities	3,004	2,725
Fair Value
Assets:
Commercial mortgage and other loans	2,883,710	1,359,422
Policy loans	1,327,485	1,323,681
Short-term Investments	37,000	0
Cash and cash equivalents	482,299	29,653
Accrued investment income	160,027	93,613
Reinsurance recoverables	29,931	227,993
Receivables from parent and affiliates	116,086	154,503
Other assets	568,981	27,120
Total assets	5,605,519	3,215,985
Liabilities:
Policyholders’ account balances - investment contracts	3,947,337	1,714,576
Cash collateral for loaned securities	3,004	2,725
Long-term debt to affiliates	319,225	0
Payables to parent and affiliates	31,775	75,990
Other liabilities	898,879	415,889
Total liabilities	5,200,220	2,209,180
Carrying Amount
Assets:
Commercial mortgage and other loans	2,832,560	1,288,846
Policy loans	1,327,485	1,323,681
Short-term Investments	37,000	0
Cash and cash equivalents	482,299	29,653
Accrued investment income	160,027	93,613
Reinsurance recoverables	28,883	217,637
Receivables from parent and affiliates	116,086	154,503
Other assets	568,981	27,120
Total assets	5,553,321	3,135,053
Liabilities:
Policyholders’ account balances - investment contracts	3,941,822	1,704,220
Cash collateral for loaned securities	3,004	2,725
Long-term debt to affiliates	320,362	0
Payables to parent and affiliates	31,775	75,990
Other liabilities	898,879	415,889
Total liabilities	5,195,842	2,198,824
Level 1 | Fair Value
Assets:
Commercial mortgage and other loans	0	0
Policy loans	0	0
Short-term Investments	37,000	0
Cash and cash equivalents	297,299	29,653
Accrued investment income	0	0
Reinsurance recoverables	0	0
Receivables from parent and affiliates	0	0
Other assets	0	0
Total assets	334,299	29,653
Liabilities:
Policyholders’ account balances - investment contracts	0	0
Cash collateral for loaned securities	0	0
Long-term debt to affiliates	0	0
Payables to parent and affiliates	0	0
Other liabilities	0	0
Total liabilities	0	0
Level 2 | Fair Value
Assets:
Commercial mortgage and other loans	0	0
Policy loans	0	0
Short-term Investments	0	0
Cash and cash equivalents	185,000	0
Accrued investment income	160,027	93,613
Reinsurance recoverables	0	0
Receivables from parent and affiliates	116,086	154,503
Other assets	134,598	27,120
Total assets	595,711	275,236
Liabilities:
Policyholders’ account balances - investment contracts	1,356,850	1,428,043
Cash collateral for loaned securities	3,004	2,725
Long-term debt to affiliates	319,225	0
Payables to parent and affiliates	31,775	75,990
Other liabilities	864,788	415,889
Total liabilities	2,575,642	1,922,647
Level 3 | Fair Value
Assets:
Commercial mortgage and other loans	2,883,710	1,359,422
Policy loans	1,327,485	1,323,681
Short-term Investments	0	0
Cash and cash equivalents	0	0
Accrued investment income	0	0
Reinsurance recoverables	29,931	227,993
Receivables from parent and affiliates	0	0
Other assets	434,383	0
Total assets	4,675,509	2,911,096
Liabilities:
Policyholders’ account balances - investment contracts	2,590,487	286,533
Cash collateral for loaned securities	0	0
Long-term debt to affiliates	0	0
Payables to parent and affiliates	0	0
Other liabilities	34,091	0
Total liabilities	$ 2,624,578	$ 286,533