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	Jun. 30, 2023	Dec. 31, 2022
Aggregate Fair Value
Loans measured at fair value	$ 720	$ 723
Past due loans of 30-89 days or more		1
Non accrual loans	3	2
Aggregate Unpaid Principal Balance
Loans measured at fair value	733	733
Past due loans of 30-89 days or more		1
Non accrual loans	3	2
Difference
Loans measured at fair value	(13)	(10)
Past due loans of 30-89 days or more		0
Non accrual loans	$ 0	$ 0