Mortgage Servicing Rights and Related Liabilities - UPB and Fair Value of Forward MSR's (Details) - Mortgage servicing rights - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Owned Service Loans [Line Items]
UPB	$ 736,071	$ 587,942
Fair Value	11,736	9,090
Agency
Owned Service Loans [Line Items]
UPB	710,997	561,656
Fair Value	11,397	8,774
Non-agency
Owned Service Loans [Line Items]
UPB	25,074	26,286
Fair Value	$ 339	$ 316