Loan Portfolio - Loan Portfolio by Portfolio Segment (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 110,430	$ 106,541
Accrued interest	453	459
Discontinued operations \| Education Lending
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	182	205
Total commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	81,568	76,509
Accrued interest	338	338
Total commercial loans \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	62,734	57,688
Total commercial loans \| Total commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	16,837	16,551
Total commercial loans \| Commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	13,941	13,707
Total commercial loans \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,896	2,844
Total commercial loans \| Commercial lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,997	2,270
Total commercial loans \| Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	208	205
Total consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	28,862	30,032
Accrued interest	114	121
Total consumer loans \| Real estate — residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	18,178	18,732
Total consumer loans \| Home equity loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	5,408	5,703
Total consumer loans \| Total residential loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	23,586	24,435
Total consumer loans \| Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	4,349	4,644
Total consumer loans \| Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 927	$ 953