Mortgage Servicing Rights - Summary of Income and Fees (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Servicing Assets at Fair Value [Line Items]
Decrease in MSR fair value due to pay-offs, pay-downs, run-off, model changes and other	$ (16)	$ (34)
Changes in fair value due to interest rate risk	21	2
Residential first mortgage loans
Servicing Assets at Fair Value [Line Items]
Servicing fees, ancillary income and late fees	54	110
Decrease in MSR fair value due to pay-offs, pay-downs, run-off, model changes and other	(16)	(34)
Changes in fair value due to interest rate risk	21	2
Gain on MSR derivatives	(35)	(32)
Net transaction costs	2	1
Total return (loss) included in net return on mortgage servicing rights	26	47
Residential first mortgage loans | Loan administration income on mortgage loans subserviced
Servicing Assets at Fair Value [Line Items]
Servicing fees, ancillary income and late fees	38	74
Charges on subserviced custodial balances	(40)	(69)
Other servicing charges	(1)	(2)
Total income on mortgage loans subserviced, included in loan administration	$ (3)	$ 3