Loans and Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2025	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest	$ 260	$ 260		$ 271
Net loans and leases	62,446	62,446		61,750
Loans and leases	$ 63,260	$ 63,260		62,565
Credit Card Workout Program rate reduction, interest rate floor		0.00%
Credit Card Workout Program term extension, maximum period		5 years
Loans modified with subsequent default, amount		$ 1	$ 8
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit Card Hardship Program, rate and payment reduction, period		6 months
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit Card Hardship Program, rate and payment reduction, period		1 year
Commercial: | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	1	1
Commercial: | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	16	16
Commercial: | Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,058	$ 4,058		3,471
Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	34,359	34,359		33,428
Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,936	13,936		14,421
Consumer:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,368	14,368		14,047
Finance and Insurance Companies | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 3,700	$ 3,700
Financial Services Industry Loans | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage contributed	23.00%	23.00%
C&I | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 397	$ 397		352
C&I | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	30,301	30,301		29,957
C&I | Commercial: | Commercial and industrial | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	164	164
Commercial Real Estate | Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,936	13,936		14,421
Commercial Real Estate | Commercial: | Commercial real estate | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	233	233
Asset Pledged as Collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net loans and leases	45,500	45,500		45,800
Asset Pledged as Collateral | C&I
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss, writeoff, collateral	13	37
Asset Pledged as Collateral | Home Equity Line of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	5	5		6
Financing receivable, allowance for credit loss, writeoff, collateral		1	$ 1
Asset Pledged as Collateral | R E Installment Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 42	$ 42		$ 36