Derivatives (Credit Derivatives) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2025	Dec. 31, 2024
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 233	$ 196
Maximum Amount of Future Payments under Credit Default Swaps	$ 11,954	$ 11,764
Weighted Average Years to Maturity	3 years 9 months 18 days	3 years 4 months 24 days
Aaa/Aa/A
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 64	$ 73
Maximum Amount of Future Payments under Credit Default Swaps	$ 4,118	$ 4,198
Weighted Average Years to Maturity	1 year 9 months 18 days	2 years 2 months 12 days
Aaa/Aa/A | Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 1
Maximum Amount of Future Payments under Credit Default Swaps	$ 72	$ 72
Weighted Average Years to Maturity	1 year 7 months 6 days	1 year 10 months 24 days
Aaa/Aa/A | Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 63	$ 72
Maximum Amount of Future Payments under Credit Default Swaps	$ 4,046	$ 4,126
Weighted Average Years to Maturity	1 year 9 months 18 days	2 years 2 months 12 days
Baa
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 147	$ 112
Maximum Amount of Future Payments under Credit Default Swaps	$ 7,470	$ 7,365
Weighted Average Years to Maturity	5 years	4 years 1 month 6 days
Baa | Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 1
Maximum Amount of Future Payments under Credit Default Swaps	$ 42	$ 102
Weighted Average Years to Maturity	4 years 1 month 6 days	1 year 7 months 6 days
Baa | Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 146	$ 111
Maximum Amount of Future Payments under Credit Default Swaps	$ 7,428	$ 7,263
Weighted Average Years to Maturity	5 years	4 years 1 month 6 days
B
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 22	$ 10
Maximum Amount of Future Payments under Credit Default Swaps	$ 323	$ 144
Weighted Average Years to Maturity	3 years 10 months 24 days	3 years 8 months 12 days
B | Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 0	$ 0
Maximum Amount of Future Payments under Credit Default Swaps	$ 19	$ 0
Weighted Average Years to Maturity	1 year	0 years
B | Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 22	$ 10
Maximum Amount of Future Payments under Credit Default Swaps	$ 304	$ 144
Weighted Average Years to Maturity	4 years 1 month 6 days	3 years 8 months 12 days
Caa
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ (1)	$ (1)
Maximum Amount of Future Payments under Credit Default Swaps	$ 15	$ 15
Weighted Average Years to Maturity	1 year 6 months	2 years
Caa | Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ (1)	$ (1)
Maximum Amount of Future Payments under Credit Default Swaps	$ 15	$ 15
Weighted Average Years to Maturity	1 year 6 months	2 years
Ba
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 2
Maximum Amount of Future Payments under Credit Default Swaps	$ 28	$ 42
Weighted Average Years to Maturity	1 year 10 months 24 days	1 year 7 months 6 days
Ba | Single name credit default swaps (3)
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 0	$ 0
Maximum Amount of Future Payments under Credit Default Swaps	$ 3	$ 17
Weighted Average Years to Maturity	5 years	1 year 1 month 6 days
Ba | Credit default swaps referencing indices
Credit Derivatives [Line Items]
Estimated Fair Value of Credit Default Swaps	$ 1	$ 2
Maximum Amount of Future Payments under Credit Default Swaps	$ 25	$ 25
Weighted Average Years to Maturity	1 year 6 months	2 years