Loans and Leases - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest	$ 227,000,000		$ 226,000,000
Net loans and leases	58,330,000,000		57,417,000,000
Loans and leases	59,045,000,000		58,102,000,000
Allowance for credit loss, writeoff, collateral	0	$ 0
C&I | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 256,000,000		124,000,000
Commercial: | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	1
Commercial: | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan grades	16
Commercial: | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 32,172,000,000		31,781,000,000
Commercial: | Commercial and industrial | Loans to mortgage companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 2,040,000,000		2,258,000,000
Percentage contributed	19.00%
Commercial: | Commercial and industrial | Finance And Insurance Companies
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,200,000,000
Commercial: | Commercial and industrial | C&I
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	30,132,000,000		29,523,000,000
Commercial: | Commercial and industrial | C&I | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	199,000,000
Commercial: | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,398,000,000		13,228,000,000
Commercial: | Commercial real estate | CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	13,398,000,000		13,228,000,000
Commercial: | Commercial real estate | CRE | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	57,000,000
Consumer:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,668,000,000		12,253,000,000
Consumer: | Consumer Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,668,000,000		12,253,000,000
Consumer: | Consumer Real Estate | HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,114,000,000		2,028,000,000
Consumer: | Consumer Real Estate | Real estate installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	10,554,000,000		10,225,000,000
Asset Pledged as Collateral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net loans and leases	39,600,000,000		38,300,000,000
Asset Pledged as Collateral | C&I
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss, writeoff, collateral	12,000,000
Asset Pledged as Collateral | HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	7,000,000		7,000,000
Asset Pledged as Collateral | Real estate installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 29,000,000		$ 26,000,000