Fair Value Measurements - Roll Forward of Financial Instruments Classified as Level 3 (Details) - Recurring - Level 3 $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) optionAdjustedSpreadPerLoan $ / loan constantPrepaymentRatePerLoan originationPull-throughRatePerLoan	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) optionAdjustedSpreadPerLoan $ / loan constantPrepaymentRatePerLoan originationPull-throughRatePerLoan	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) $ / loan constantPrepaymentRatePerLoan optionAdjustedSpreadPerLoan originationPull-throughRatePerLoan
Assets
Balance at Beginning of Period	$ 519	$ 504	$ 445	$ 539
Total Gains (Losses) Recorded in Earnings	53	(7)	(82)	(142)
Purchases / Closings	144	243	337	513
Sales	(32)	(96)	(32)	(96)
Settlement	0	0	0	0
Transfers Out	(37)	(186)	(21)	(356)
Balance at End of Period	647	458	647	458
(Dollars in millions)
Balance at Beginning of Period		(70)		(35)
Total Gains (Losses) Recorded in Earnings		0		(35)
Purchases / Closings		0		0
Sales		0		0
Settlement		70		70
Transfers Out		0		0
Balance at End of Period		0		0
Home equity
Assets
Balance at Beginning of Period		2		2
Total Gains (Losses) Recorded in Earnings		0		0
Purchases / Closings		0		0
Sales		0		0
Settlement		0		0
Transfers Out		0		0
Balance at End of Period		2		2
Mortgage servicing rights
Assets
Balance at Beginning of Period	523	428	392	329
Total Gains (Losses) Recorded in Earnings	34	(54)	73	(20)
Purchases / Closings	97	64	189	129
Sales	(32)	(96)	(32)	(96)
Settlement	0	0	0	0
Transfers Out	0	0	0	0
Balance at End of Period	622	342	622	342
(Dollars in millions)
Servicing asset	$ 622		$ 622		$ 392
Mortgage servicing rights | Weighted Average | Option adjusted spread
(Dollars in millions)
Servicing asset, measurement input | optionAdjustedSpreadPerLoan	0.062		0.062		0.071
Mortgage servicing rights | Weighted Average | Constant prepayment rate
(Dollars in millions)
Servicing asset, measurement input | constantPrepaymentRatePerLoan	0.079		0.079		0.092
Mortgage servicing rights | Weighted Average | Weighted average cost to service per loan
(Dollars in millions)
Servicing asset, measurement input | $ / loan	79		79		80
Mortgage servicing rights | Minimum | Option adjusted spread
(Dollars in millions)
Servicing asset, measurement input | optionAdjustedSpreadPerLoan	0.039		0.039		0.039
Mortgage servicing rights | Minimum | Constant prepayment rate
(Dollars in millions)
Servicing asset, measurement input | constantPrepaymentRatePerLoan	0		0		0
Mortgage servicing rights | Minimum | Weighted average cost to service per loan
(Dollars in millions)
Servicing asset, measurement input | $ / loan	67		67		67
Mortgage servicing rights | Maximum | Option adjusted spread
(Dollars in millions)
Servicing asset, measurement input | optionAdjustedSpreadPerLoan	0.216		0.216		0.216
Mortgage servicing rights | Maximum | Constant prepayment rate
(Dollars in millions)
Servicing asset, measurement input | constantPrepaymentRatePerLoan	0.098		0.098		0.111
Mortgage servicing rights | Maximum | Weighted average cost to service per loan
(Dollars in millions)
Servicing asset, measurement input | $ / loan	90		90		90
Rate lock commitments
Assets
Balance at Beginning of Period	$ (4)	74	$ 53	208
Total Gains (Losses) Recorded in Earnings	19	47	(155)	(122)
Purchases / Closings	47	179	148	384
Sales	0	0	0	0
Settlement	0	0	0	0
Transfers Out	(37)	(186)	(21)	(356)
Balance at End of Period	25	114	25	114
(Dollars in millions)
Derivative asset	$ 25		$ 25		$ 53
Rate lock commitments | Weighted Average | Origination pull-through rate
(Dollars in millions)
Derivative asset, measurement input (as a percent) | originationPull-throughRatePerLoan	0.762		0.762		0.728
DOJ Liability
(Dollars in millions)
Balance at Beginning of Period		(70)		(35)
Total Gains (Losses) Recorded in Earnings		0		(35)
Purchases / Closings		0		0
Sales		0		0
Settlement		70		70
Transfers Out		0		0
Balance at End of Period		$ 0		$ 0