Mortgage Servicing Rights and Related Liabilities - MSRs and Related Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Mortgage Servicing Rights [Line Items]
Excess spread financing at fair value	$ 366	$ 386
Mortgage servicing rights financing at fair value	32	32
MSR related liabilities - nonrecourse at fair value	398	418
Mortgage servicing rights
Mortgage Servicing Rights [Line Items]
MSRs at fair value	$ 11,345	$ 11,736