Mortgage Servicing Assets - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Commercial Mortgage Backed Securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	$ 180	$ 159
Amortization of servicing commercial mortgage loans	63	62
Residential mortgage-backed securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	19	18
Amortization of servicing commercial mortgage loans	$ 5	$ 4