Certain Long-Duration Contracts with Guarantees (Sales Inducements) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement in Deferred Sales Inducements [Roll Forward]
Beginning balance	$ 812,724	$ 889,598	$ 1,020,786
Capitalization	1,084	797	2,888
Amortization - Impact of assumption and experience unlocking and true-ups	103,057	100,222	(5,713)
Amortization - All other	(150,083)	(146,620)	(149,236)
Change in unrealized investment gains and losses	(52,184)	(31,273)	20,873
Ending balance	$ 714,598	$ 812,724	$ 889,598