Loans and Leases - Troubled Debt Restructuring Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	$ 307	$ 206
Loan loss reserves	963	200	$ 180	$ 189
Allowance For TDRs To Recorded Investment Of TDRs
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan loss reserves	$ 12	$ 20
Ratio of the allowance for loan losses to loans	4.00%	10.00%
Loans Held For Sale, Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings loans	$ 42	$ 51
Consumer | Consumer real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDRS maturities	30 years
Loan loss reserves	$ 242	28	37	53
Consumer | Consumer real estate | Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR, reduction of interest rate by increment, basis points	25.00%
Modified interest rate increase	2.00%
Consumer | Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR, reduction of interest rate by increment, basis points	25.00%
Modified interest rate increase	1.00%
TDRS maturities	40 years
Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan loss reserves	$ 26	$ 13	$ 13	$ 10
Consumer | Credit Card and Other | Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit card workout program, granted rate reduction	0.00%
Minimum | Consumer | Consumer real estate | Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	1.00%
Modified interest rate time period	5 years
Minimum | Consumer | Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate	2.00%
Modified interest rate time period	5 years
Minimum | Consumer | Credit Card and Other | Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period	6 months
Minimum | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period	6 months
Maximum | Consumer | Consumer real estate | Heloc And Real Estate Installment Classes
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period	5 years
Maximum | Consumer | Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified interest rate time period	5 years
Maximum | Consumer | Credit Card and Other | Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Payment reductions, time period	1 year
Credit card workout program, term extension	5 years
Maximum | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forbearance agreements time period	12 months