Investments (Realized Investment Gains Losses, Net) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022		Sep. 30, 2023	Sep. 30, 2022
Schedule Of Gain Loss On Investments [Line Items]
Realized Investment gains (losses), net	$ (468,256)	$ 97,271	[1]	$ (581,241)	$ 810,771	[2]
Fixed maturities
Schedule Of Gain Loss On Investments [Line Items]
Realized Investment gains (losses), net	(8,931)	(5,888)		(17,154)	(69,326)
Commercial mortgage and other loans
Schedule Of Gain Loss On Investments [Line Items]
Realized Investment gains (losses), net	(5,059)	(7,513)		(7,143)	(13,872)
Other invested assets
Schedule Of Gain Loss On Investments [Line Items]
Realized Investment gains (losses), net	10,856	(75,864)		24,052	(72,328)
Derivatives
Schedule Of Gain Loss On Investments [Line Items]
Realized Investment gains (losses), net	(465,176)	186,514		(582,846)	966,487
Short-term investments and cash equivalents
Schedule Of Gain Loss On Investments [Line Items]
Realized Investment gains (losses), net	$ 54	$ 22		$ 1,850	$ (190)

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

[2] Prior period amounts adjusted for the implementation of ASU 2018-12: Targeted Improvements to the Accounting for Long-Duration Contracts.