Investments (Realized Investment Gains Losses, Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ (7,512)	$ (5,056)	$ 5,553	$ (11,166)
Fixed maturities
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(42)	(384)	(643)	(3,479)
Commercial mortgage and other loans
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(15)	21	(88)	33
Other invested assets
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	1	0	(59)	11
Derivatives
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	(7,493)	(4,689)	6,378	(7,733)
Short-term investments and cash equivalents
Schedule Of Gain Loss On Investments [Line Items]
Realized investment gains (losses), net	$ 37	$ (4)	$ (35)	$ 2