Mortgage Servicing Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Commercial Mortgage Backed Securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	$ 87	$ 78
Amortization of servicing commercial mortgage loans	31	32
Residential mortgage-backed securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	9	9
Amortization of servicing commercial mortgage loans	$ 2	$ 2