Mortgage Servicing Rights and Related Liabilities - UPB related to owned MSRs (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Mortgage servicing rights
Owned Service Loans [Line Items]
UPB	$ 733,752	$ 736,071
Fair Value	11,345	11,736
Forward MSRs Sold, Subservicing Retained
Owned Service Loans [Line Items]
UPB	1,299		$ 3,003
Agency | Mortgage servicing rights
Owned Service Loans [Line Items]
UPB	708,803	710,997
Fair Value	11,012	11,397
Non-agency | Mortgage servicing rights
Owned Service Loans [Line Items]
UPB	24,949	25,074
Fair Value	$ 333	$ 339