Investments (Realized Investment Gains Losses, Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Gain (Loss) on Investments [Line Items]
Realized investment gains (losses), net	$ (5,295,406)	$ (62,976)	$ (116,749)
Fixed Maturities
Schedule of Gain (Loss) on Investments [Line Items]
Realized investment gains (losses), net	(3,514)	(7,236)	46,738
Commercial mortgage and other loans
Schedule of Gain (Loss) on Investments [Line Items]
Realized investment gains (losses), net	1,535	(226)	297
Other Invested Assets
Schedule of Gain (Loss) on Investments [Line Items]
Realized investment gains (losses), net	(2,737)	(287)	(3,400)
Derivatives
Schedule of Gain (Loss) on Investments [Line Items]
Realized investment gains (losses), net	(5,291,043)	(55,003)	(160,368)
Short-term investments and cash equivalents
Schedule of Gain (Loss) on Investments [Line Items]
Realized investment gains (losses), net	$ 353	$ (224)	$ (16)