Derivative Instruments (Exposure from Credit Derivatives by Rating of the Underlying Credits) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2022	Dec. 31, 2021
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (31)	$ 28
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 1,816	$ 1,321
Derivative Average Remaining Maturity	[1],[3]	8 years 4 months 24 days	9 years
Standard Poors AAA To A Minus Ratings [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (31)	$ 28
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 600	$ 600
Derivative Average Remaining Maturity	[1],[3]	14 years	14 years 2 months 12 days
Standard Poors AAA To A Minus Ratings [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (31)	$ 28
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 600	$ 600
Derivative Average Remaining Maturity	[1],[3]	14 years	14 years 2 months 12 days
Standard Poors BBB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 1	$ 1
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 181	$ 141
Derivative Average Remaining Maturity	[1],[3]	2 years 8 months 12 days	2 years 4 months 24 days
Standard Poors BBB Rating [Member] | Credit Default Swaps Referencing Indices [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 0	$ 0
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 1,015	$ 565
Derivative Average Remaining Maturity	[1],[3]	6 years 1 month 6 days	5 years 1 month 6 days
Standard Poors BBB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 1	$ 1
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 1,196	$ 706
Derivative Average Remaining Maturity	[1],[3]	5 years 7 months 6 days	4 years 7 months 6 days
Standard & Poor's, BB Rating [Member]
Credit Derivatives [Line Items]
Derivative Average Remaining Maturity	[1],[2]	3 years 7 months 6 days	3 years 6 months
Standard & Poor's, BB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (1)	$ (1)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	20	15
Standard & Poor's, BB Rating [Member] | Credit Default Subtotal [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	(1)	(1)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 20	$ 15

[1] The rating agency designations are based on ratings from Standard and Poor’s (“S&P”).

[2] Assumes the value of the referenced credit obligations is zero.

[3] The weighted average years to maturity of the credit default swaps is calculated based on weighted average notional amounts.