Loan Portfolio (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 101,854	$ 101,185
Discontinued Operations | Education Lending
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	567	710
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	70,836	71,980
Accrued interest	113
Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	50,525	52,907
Accrued interest	198	241
Commercial Loans | Commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	14,244	12,687
Commercial Loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,996	1,987
Commercial Loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	16,240	14,674
Commercial Loans | Commercial lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,071	4,399
Commercial Loans | Commercial credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	139	127
Commercial Loans | Collateral pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	16	23
Consumer Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	31,018	29,205
Accrued interest	85
Consumer Loans | Real estate — residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	15,756	9,298
Consumer Loans | Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	8,467	9,360
Consumer Loans | Residential - prime loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	24,223	18,658
Consumer Loans | Consumer direct loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	5,753	4,714
Consumer Loans | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	972	989
Consumer Loans | Consumer indirect loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	70	4,844
Consumer Loans | Commercial credit card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 972	$ 989