Derivatives (Credit Risk on Freestanding Derivatives) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Credit Derivatives [Line Items]
Collateral Amount Not Provided Due to Downgrade Threshold	$ 15
Estimated fair value of derivatives in a net liability position (1)	1,185	$ 959
Derivative assets	11,866	10,084
Derivative liabilities	4,229	3,737
Fixed maturity securities AFS
Credit Derivatives [Line Items]
Estimated fair value of collateral provided:	1,224	1,063
Accrued Liabilities [Member]
Credit Derivatives [Line Items]
Derivative assets	92	111
Derivative liabilities	(58)	(21)
Derivatives Subject to Credit-Contingent Provisions
Credit Derivatives [Line Items]
Estimated fair value of derivatives in a net liability position (1)	1,182	874
Derivatives Subject to Credit-Contingent Provisions | Fixed maturity securities AFS
Credit Derivatives [Line Items]
Estimated fair value of collateral provided:	1,222	983
Derivatives Not Subject to Credit-Contingent Provisions
Credit Derivatives [Line Items]
Estimated fair value of derivatives in a net liability position (1)	3	85
Derivatives Not Subject to Credit-Contingent Provisions | Fixed maturity securities AFS
Credit Derivatives [Line Items]
Estimated fair value of collateral provided:	$ 2	$ 80