Business and Basis of Presentation (Cost Of Reinsurance) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021	Jan. 01, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance prior to transition	$ 13,198,477	$ 12,664,445	$ 12,093,263	$ 11,660,527
Unwinding amounts related to unrealized investment gains and losses and other activity		$ (12,611)		$ (215,658)
Amounts related to unrealized investment gains and losses after transition	12,979,687		11,902,756
Balance after transition	$ 218,790		$ 190,507
Variable/Universal Life | Other liabilities
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance prior to transition					$ 437,315
Amounts related to unrealized investment gains and losses after transition					191,098
Balance after transition					628,413
Variable/Universal Life | As Previously Reported | Other liabilities
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance prior to transition						$ 602,294
Variable/Universal Life | Unwinding amounts related to unrealized investment gains and losses | Other liabilities
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Unwinding amounts related to unrealized investment gains and losses and other activity					(246,899)
Variable/Universal Life | Balance prior to transition, excluding amounts related to unrealized investment gains and losses | Other liabilities
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance prior to transition					355,395
Variable/Universal Life | Impact from updates to certain universal life contract liabilities | Other liabilities
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Unwinding amounts related to unrealized investment gains and losses and other activity					$ 81,920