Loans and Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest	$ 281	$ 281		$ 287
Net loans and leases	61,622	61,622		60,519
Loans and leases	$ 62,445	62,445		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 (current year less than)		$ 1	$ 21
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	$ 3,244	$ 3,244		2,024
Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	33,092	33,092		32,633
Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,705	14,705		14,216
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	21.00%	21.00%
General C I | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 376	$ 376		250
General C I | Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	29,848	29,848		30,609
General C I | Commercial: | Commercial and industrial | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	134	134
Commercial Real Estate | Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,705	14,705		14,216
Commercial Real Estate | Commercial: | Commercial real estate | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	242	242
Asset Pledged as Collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net loans and leases	46,600	46,600		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	27	67
Asset Pledged as Collateral | Home Equity Line of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	6	6		6
Asset Pledged as Collateral | R E Installment Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 28	$ 28		$ 27