Investments Summary of AFS Securities with Unrealized Losses (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less Than 12 Months: Estimated Fair Value	$ 2,833	$ 1,412
Less Than 12 Months: Unrealized Losses	4	6
12 Months or More: Estimated Fair Value	683	912
12 Months or More: Unrealized Losses	20	23
Unrealized Loss Position, Total Fair Value	3,516	2,324
Unrealized Loss Position, Total Accumulated Loss	24	29
US Treasury Notes
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less Than 12 Months: Estimated Fair Value	2,066
Less Than 12 Months: Unrealized Losses	1
12 Months or More: Estimated Fair Value	0
12 Months or More: Unrealized Losses	0
Unrealized Loss Position, Total Fair Value	2,066
Unrealized Loss Position, Total Accumulated Loss	1
Residential Mortgage Backed Securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less Than 12 Months: Estimated Fair Value	47	62
Less Than 12 Months: Unrealized Losses	1	3
12 Months or More: Estimated Fair Value	250	244
12 Months or More: Unrealized Losses	19	19
Unrealized Loss Position, Total Fair Value	297	306
Unrealized Loss Position, Total Accumulated Loss	20	22
Multifamily \| MBS - GSEs
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less Than 12 Months: Estimated Fair Value	720
Less Than 12 Months: Unrealized Losses	2
12 Months or More: Estimated Fair Value	433
12 Months or More: Unrealized Losses	1
Unrealized Loss Position, Total Fair Value	1,153
Unrealized Loss Position, Total Accumulated Loss	$ 3
Multifamily \| MBS - GSEs \| Fannie Mae
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less Than 12 Months: Estimated Fair Value		1,350
Less Than 12 Months: Unrealized Losses		3
12 Months or More: Estimated Fair Value		668
12 Months or More: Unrealized Losses		4
Unrealized Loss Position, Total Fair Value		2,018
Unrealized Loss Position, Total Accumulated Loss		$ 7

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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