Loans and ACL - Types of Modifications and Allowance at Period End (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Newly Designated TDRs | Commercial:
Financing Receivable, Troubled Debt Restructuring [Line Items]
ALLL at Period End	$ 17	$ 24	$ 15
Financing Receivable, Troubled Debt Restructuring, Premodification	193	290	101
Newly Designated TDRs | Consumer:
Financing Receivable, Troubled Debt Restructuring [Line Items]
ALLL at Period End	36	49	64
Financing Receivable, Troubled Debt Restructuring, Premodification	606	797	493
Newly Designated TDRs | Credit card
Financing Receivable, Troubled Debt Restructuring [Line Items]
ALLL at Period End	5	10	9
Financing Receivable, Troubled Debt Restructuring, Premodification	12	28	18
Newly Designated TDRs | Rate | Commercial:
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	35	89	93
Newly Designated TDRs | Rate | Consumer:
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	284	543	445
Newly Designated TDRs | Rate | Credit card
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	11	29	24
Newly Designated TDRs | Structure | Commercial:
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	130	176	12
Newly Designated TDRs | Structure | Consumer:
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	312	240	38
Newly Designated TDRs | Structure | Credit card
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	0	0	0
Re-Modification of Previously Designated TDRs | Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	61	41	53
Re-Modification of Previously Designated TDRs | Structure
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs	$ 38	$ 22	$ 23