Loans and Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest	$ 294	$ 294		$ 287
Net loans and leases	61,960	61,960		60,519
Loans and leases	$ 62,781	62,781		61,292
Financing receivable, allowance for credit loss, writeoff, collateral		$ 1	$ 1
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		$ 8	$ 25
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: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 33,452	$ 33,452		32,633
Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,669	14,669		14,216
Loans to mortgage companies | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 2,934	$ 2,934		2,024
Percentage contributed	20.00%	20.00%
Finance And Insurance Companies | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 3,800	$ 3,800
General C I | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	310	310		250
General C I | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	30,518	30,518		30,609
General C I | Commercial: | Commercial and industrial | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	121	121
Commercial Real Estate | Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,669	14,669		14,216
Commercial Real Estate | Commercial: | Commercial real estate | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	189	189
Asset Pledged as Collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net loans and leases	46,500	46,500		46,100
Asset Pledged as Collateral | General C I
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss, writeoff, collateral	19	40
Asset Pledged as Collateral | Home Equity Line of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	7	7		6
Asset Pledged as Collateral | R E Installment Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 27	$ 27		$ 27