Liability For Future Policy Benefits (Future Policy Benefits) (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022		Sep. 30, 2022	Dec. 31, 2021
Insurance [Abstract]
Benefit reserves, end of period, post-flooring	$ 6,939,033			$ 6,856,384
Deferred profit liability, end of period, post-flooring	14,868			17,767
Additional insurance reserves, including amounts in AOCI, end of period, post-flooring	13,198,477	$ 12,664,445		12,093,263	$ 11,660,527
Subtotal of amounts disclosed above	20,152,378			18,967,414
Other Future Policy Benefits reserves	1,104,756			1,036,278
Total Future policy Benefits	$ 21,257,134	$ 20,829,033	[1]	$ 20,003,692

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