Loans, Leases, and Allowance for Credit Losses (Narrative) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) mo	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Net unamortized purchase premiums, discounts, and deferred loan fees and cost	$ 37,000,000	$ 49,000,000
Accrued interest receivable	$ 299,000,000	$ 247,000,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Loans and leases, net of unearned income and fees	$ 57,779,000,000	$ 55,653,000,000
Loans held for sale	53,000,000	8,000,000
Payments for origination and purchases of loans held-for-sale	678,000,000	659,000,000	$ 1,700,000,000
Held-for-sale loans sold	632,000,000	716,000,000	1,683,000,000
Principal balance of loans sold, serviced loans	400,000,000	3,500,000,000
Income from loans sold	16,000,000	14,000,000	$ 34,000,000
Financing receivable, commitments threshold for evaluating collectively or individually	1,000,000
Recorded investment in TDR loans modified with interest rates below market	$ 264,000,000	235,000,000
Financing receivable, minimum number of months for borrower to meet terms for TDR status | mo	6
Unfunded lending commitments	$ 22,000,000	7,000,000
Financing receivable, modifications, subsequent default, recorded investment		10,000,000
Real estate acquired through foreclosure (less than)	0	0
Mortgage loans in process of foreclosure	11,000,000	10,000,000
Asset Pledged as Collateral without Right
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	36,300,000,000	27,600,000,000
Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		38,000,000
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	$ 13,371,000,000	12,739,000,000
Financing receivable, period once past due, charged off or charged down (in days)	180 days
Recorded investment in TDR loans modified with interest rates below market	$ 192,000,000
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
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	$ 13,820,000,000	12,419,000,000
Financing receivable, period once past due, charged off or charged down (in days)	180 days
Recorded investment in TDR loans modified with interest rates below market	$ 3,000,000
Consumer | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		5,000,000
Commercial Mortgage-Backed Securities
Financing Receivable, Allowance for Credit Losses [Line Items]
Principal balance of loans sold, serviced loans	3,000,000,000
Interest Rate Below Market Reduction
Financing Receivable, Allowance for Credit Losses [Line Items]
Accumulated modified in period		63,000,000
Payment deferral
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	2,000,000	32,000,000
Payment deferral | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	1,000,000	3,000,000
Payment deferral | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	0
Payment deferral | Commercial real estate | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		0
Payment deferral | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	0
Payment deferral | Consumer | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		0
Principal forgiveness
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	1,000,000	7,000,000
Principal forgiveness | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		1,000,000
Principal forgiveness | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	0
Principal forgiveness | Commercial real estate | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		0
Principal forgiveness | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	1,000,000
Principal forgiveness | Consumer | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market		1,000,000
Land Acquisition and Development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	$ 219,000,000	$ 262,000,000
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