Mortgage Servicing Assets - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Commercial Mortgage Backed Securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	$ 307	$ 284
Amortization of servicing commercial mortgage loans	94	93
Residential mortgage-backed securities
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	30	29
Amortization of servicing commercial mortgage loans	$ 9	$ 8