Mortgage Servicing Assets - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Commercial Mortgage Backed Securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	$ 159	$ 143
Amortization of servicing commercial mortgage loans	62	62
Residential mortgage-backed securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	18	19
Amortization of servicing commercial mortgage loans	$ 4	$ 7