Loan Portfolio - Loans by Category (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 106,600	$ 101,854
Accrued interest	193	198
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	73,920	70,836
Accrued interest	117	113
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	32,680	31,018
Accrued interest	75	85
Commercial and Industrial | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	52,815	50,525
Commercial mortgage | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	15,124	14,244
Construction | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,065	1,996
Commercial real estate loans | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	17,189	16,240
Commercial lease financing | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	3,916	4,071
Real estate — residential mortgage | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	17,181	15,756
Home equity loans | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	8,258	8,467
Residential - Prime Loans | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	25,439	24,223
Consumer direct loans | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	6,249	5,753
Credit cards | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	930	972
Consumer indirect loans | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	62	70
Commercial credit card | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	147	139
Commercial credit card | Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	930	972
Collateral pledged | Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	14	16
Education Lending | Discontinued Operations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 531	$ 567