Goodwill and Mortgage Servicing Rights - Mortgage Fees and Related Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Risk management:
All other	$ 2	$ 1	$ 2	$ 4
Mortgage fees and related income	262	429	1,051	1,239
Consumer & Community Banking
CCB mortgage fees and related income
Net production revenue	108	158	296	451
Operating revenue:
Loan servicing revenue	435	493	1,389	1,533
Changes in MSR asset fair value due to collection/realization of expected cash flows	(195)	(200)	(542)	(617)
Total operating revenue	240	293	847	916
Risk management:
Changes in MSR asset fair value due to market interest rates and other	150	(67)	636	(188)
Other changes in MSR asset fair value due to other inputs and assumptions in model	(52)	1	(59)	(35)
Change in derivative fair value and other	(186)	43	(671)	91
Total risk management	(88)	(23)	(94)	(132)
Total net mortgage servicing revenue	152	270	753	784
Mortgage fees and related income	$ 260	$ 428	$ 1,049	$ 1,235