Liability for Future Policy Benefits (Future Policy Benefits Reconciliation) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Insurance [Abstract]
Benefit reserves, end of period, post-flooring	$ 7,727,206	$ 7,128,184		$ 8,690,057
Deferred profit liability, end of period, post-flooring	14,818	18,193		15,765
Additional insurance reserves, including amounts in AOCI, end of period, post-flooring	14,280,792	12,664,445		11,660,527
Subtotal of amounts disclosed above	22,022,816	19,810,822		20,366,349
Other future policy benefit reserves	1,182,389	1,018,211		1,144,400
Future policy benefits	$ 23,205,205	$ 20,829,033	[1]	$ 21,510,749

[1] Prior period amounts reflect the implementation of Accounting Standard Update ("ASU") 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.