Mortgage Servicing Assets - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Commercial Mortgage Backed Securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	$ 284	$ 234
Amortization of servicing commercial mortgage loans	93	92
Residential mortgage-backed securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	29	25
Amortization of servicing commercial mortgage loans	$ 8	$ 7