Loans, Leases, and Allowance for Credit Losses (Narrative) (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) mo	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Net unamortized purchase premiums, discounts, and deferred loan fees and cost	$ 49,000,000	$ 83,000,000
Accrued interest receivable	247,000,000	161,000,000
Loans and leases, net of unearned income and fees	$ 55,653,000,000	$ 50,851,000,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Loans held for sale	$ 8,000,000	$ 83,000,000
Held-for-sale loans sold	700,000,000	1,700,000,000	$ 1,800,000,000
Payments for origination and purchases of loans held-for-sale	700,000,000	1,700,000,000	1,800,000,000
Principal balance of loans sold, serviced loans	3,500,000,000	3,300,000,000
Income from loans sold	14,000,000	34,000,000	$ 54,000,000
Financing receivable, commitments threshold for evaluating collectively or individually	$ 1,000,000
Financing receivable, minimum number of months for borrower to meet terms for TDR status | mo	6
Unfunded lending commitments	$ 7,000,000	10,000,000
Recorded investment in TDR loans modified with interest rates below market	235,000,000	326,000,000
Mortgage loans in process of foreclosure	10,000,000	10,000,000
Asset Pledged as Collateral without Right
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	27,600,000,000	26,800,000,000
Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	38,000,000	105,000,000
Financing receivable, modifications, subsequent default, recorded investment	10,000,000	3,000,000
Doubtful
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	0	0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	$ 12,739,000,000	12,198,000,000
Financing receivable, period once past due, charged off or charged down (in days)	180 days
Commercial real estate | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	$ 10,000,000	16,000,000
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	$ 12,419,000,000	10,213,000,000
Financing receivable, period once past due, charged off or charged down (in days)	180 days
Consumer | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	$ 5,000,000	5,000,000
Interest Rate Below Market, Including Multiple Modification Types
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	63,000,000	100,000,000
Land Acquisition and Development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	$ 262,000,000	$ 160,000,000
Closed-End Consumer Loans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, period once past due, charged off or charged down (in days)	120 days