Mortgage Servicing Rights and Related Liabilities - UPB related to owned MSRs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Owned Service Loans [Line Items]
Gain on Sale of Excess Yield	$ 33
Sale of Excess Yield, Total Proceeds	294
Sale of Excess Yield, UPB	41,958
Mortgage servicing rights
Owned Service Loans [Line Items]
UPB	528,324	$ 411,382
Fair Value	8,504	6,654
Forward MSRs Sold
Owned Service Loans [Line Items]
UPB	23,789		$ 20,723
Forward MSRs Sold, Subservicing Retained
Owned Service Loans [Line Items]
UPB	22,640		$ 19,692
Agency | Mortgage servicing rights
Owned Service Loans [Line Items]
UPB	501,315	380,502
Fair Value	8,193	6,322
Non-agency | Mortgage servicing rights
Owned Service Loans [Line Items]
UPB	27,009	30,880
Fair Value	$ 311	$ 332