Fair Value Measurements - Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance for Residential Mortgage Loans Measured at Fair Value (Details) - Residential mortgage loans - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Aggregate Fair Value
Residential mortgage loans measured at fair value	$ 554	$ 682
Past due loans of 30-89 days	1	1
Nonaccrual loans	2	2
Past due loans of 90 days or more		1
Aggregate Unpaid Principal Balance
Residential mortgage loans measured at fair value	556	693
Past due loans of 30-89 days	1	1
Nonaccrual loans	$ 2	2
Past due loans of 90 days or more		$ 1