Loans and Leases - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest	$ 180	$ 85
Loans, net of unearned income	58,232	$ 31,061
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	33,104
Commercial | C&I | Paycheck Protection Plan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 4,100