Investments (Realized Investment Gains Losses, Net) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ 784,107	$ 76,608
Fixed maturities
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(36,721)	(2,738)
Commercial mortgage and other loans
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(603)	238
Other invested assets
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	1,642	22
Derivatives
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	820,053	79,091
Short-term investments and cash equivalents
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ (264)	$ (5)