Fair Value of Assets and Liabilities (Financial Instruments where Carrying Amounts and Fair Values May Differ) (Details) - USD ($) $ in Thousands		Sep. 30, 2025	Dec. 31, 2024
Assets:
Policy loans		$ 1,625,194	$ 1,541,480
Cash and cash equivalents		2,218,493	3,325,698
Accrued investment income	[1]	563,184	466,394
Reinsurance recoverables and deposit receivables		51,591,454	48,247,817
Receivables from parent and affiliates		646,006	678,028
Liabilities
Cash collateral for loaned securities		123,845	121,372
Fair Value
Assets:
Commercial mortgage and other loans		9,696,602	7,534,909
Policy loans		1,625,194	1,541,480
Short-term investments		44,600	21,101
Cash and cash equivalents		262,626	474,415
Accrued investment income		563,184	466,394
Reinsurance recoverables and deposit receivables		3,731,605	2,355,489
Receivables from parent and affiliates		158,073	157,566
Other assets		253,078	203,493
Total assets		16,334,962	12,754,847
Liabilities
Policyholders’ account balances - investment contracts		14,047,199	10,811,361
Cash collateral for loaned securities		123,845	121,372
Reinsurance and funds withheld payable		2,624,733	2,602,140
Payables to parent and affiliates		24,124	38,571
Other liabilities		771,474	880,884
Total liabilities		17,591,375	14,454,328
Carrying Amount
Assets:
Commercial mortgage and other loans		9,702,695	7,759,323
Policy loans		1,625,194	1,541,480
Short-term investments		44,600	21,101
Cash and cash equivalents		262,626	474,415
Accrued investment income		563,184	466,394
Reinsurance recoverables and deposit receivables		3,732,816	2,357,292
Receivables from parent and affiliates		158,073	157,566
Other assets		253,078	203,493
Total assets		16,342,266	12,981,064
Liabilities
Policyholders’ account balances - investment contracts		14,058,318	10,826,931
Cash collateral for loaned securities		123,845	121,372
Reinsurance and funds withheld payable		2,624,733	2,602,140
Payables to parent and affiliates		24,124	38,571
Other liabilities		771,475	880,884
Total liabilities		17,602,495	14,469,898
Level 1 | Fair Value
Assets:
Commercial mortgage and other loans		0	0
Policy loans		0	0
Short-term investments		44,600	21,101
Cash and cash equivalents		262,626	474,415
Accrued investment income		0	0
Reinsurance recoverables and deposit receivables		0	0
Receivables from parent and affiliates		0	0
Other assets		0	0
Total assets		307,226	495,516
Liabilities
Policyholders’ account balances - investment contracts		0	0
Cash collateral for loaned securities		0	0
Reinsurance and funds withheld payable		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		0	0
Accrued investment income		563,184	466,394
Reinsurance recoverables and deposit receivables		0	0
Receivables from parent and affiliates		158,073	157,566
Other assets		253,078	203,493
Total assets		974,335	827,453
Liabilities
Policyholders’ account balances - investment contracts		768,550	815,520
Cash collateral for loaned securities		123,845	121,372
Reinsurance and funds withheld payable		2,624,733	2,602,140
Payables to parent and affiliates		24,124	38,571
Other liabilities		740,680	849,278
Total liabilities		4,281,932	4,426,881
Level 3 | Fair Value
Assets:
Commercial mortgage and other loans		9,696,602	7,534,909
Policy loans		1,625,194	1,541,480
Short-term investments		0	0
Cash and cash equivalents		0	0
Accrued investment income		0	0
Reinsurance recoverables and deposit receivables		3,731,605	2,355,489
Receivables from parent and affiliates		0	0
Other assets		0	0
Total assets		15,053,401	11,431,878
Liabilities
Policyholders’ account balances - investment contracts		13,278,649	9,995,841
Cash collateral for loaned securities		0	0
Reinsurance and funds withheld payable		0	0
Payables to parent and affiliates		0	0
Other liabilities		30,794	31,606
Total liabilities		$ 13,309,443	$ 10,027,447

[1] See Note 4 for details of balances associated with variable interest entities.