Derivative Instruments (Exposure from Credit Derivatives by Rating of the Underlying Credits) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2025	Dec. 31, 2024
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (19)	$ (2)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 4,165	$ 2,661
Derivative Average Remaining Maturity	[1],[3]	6 years 3 months 18 days	6 years 9 months 18 days
Standard Poors AAA To A Minus Ratings [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (21)	$ (5)
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 410	$ 410
Derivative Average Remaining Maturity	[1],[3]	17 years 3 months 18 days	17 years 6 months
Standard Poors BBB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 3	$ 3
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 155	$ 150
Derivative Average Remaining Maturity	[1],[3]	2 years 2 months 12 days	2 years 3 months 18 days
Standard Poors BBB Rating [Member] | Credit Default Swaps Referencing Indices [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ (1)	$ 0
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 3,585	$ 2,086
Derivative Average Remaining Maturity	[1],[3]	5 years 2 months 12 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]	$ 2	$ 3
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 3,740	$ 2,236
Derivative Average Remaining Maturity	[1],[3]	5 years 1 month 6 days	4 years 10 months 24 days
Standard & Poor's, BB Rating [Member]
Credit Derivatives [Line Items]
Derivative Average Remaining Maturity	[1],[3]	1 year 2 months 12 days	1 year 6 months
Standard & Poor's, BB Rating [Member] | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 0	$ 0
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 5	$ 5
Standard & Poor's, B Rating
Credit Derivatives [Line Items]
Derivative Average Remaining Maturity	[1],[3]	1 year	1 year 2 months 12 days
Standard & Poor's, B Rating | Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Credit Derivative Current Fair Value	[1]	$ 0	$ 0
Maximum Potential Future Exposure on Credit Risk Derivatives	[1],[2]	$ 10	$ 10

[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.