Loans, Leases, and Allowance for Credit Losses (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Net unamortized purchase premiums, discounts, and deferred loan fees and cost	$ 32,000,000		$ 37,000,000
Accrued interest receivable	$ 300,000,000		$ 299,000,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets		Other assets
Total loans	$ 58,109,000,000		$ 57,779,000,000
Loans held for sale	12,000,000		53,000,000
Principal balance of loans sold, serviced loans	500,000,000		400,000,000
Total income from loans sold	1,000,000	$ 5,000,000
Interest income	0	0
Financing receivable, commitments threshold for evaluating collectively or individually	1,000,000
Amortized cost basis	123,000,000	97,000,000
Unfunded lending commitments on troubled debt restructuring	3,000,000	8,000,000
Real estate acquired through foreclosure	1,000,000		0
Mortgage loans in process of foreclosure	11,000,000
Doubtful
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,000,000		0
Nonaccrual
Financing Receivable, Allowance for Credit Losses [Line Items]
Modified, still in default	1,000,000
Principal forgiveness
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	2,000,000	0
Payment deferral
Financing Receivable, Allowance for Credit Losses [Line Items]
Modified, still in default	18,000,000	1,000,000
Amortized cost basis	0	0
Asset Pledged as Collateral without Right
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	38,700,000,000		36,300,000,000
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	30,479,000,000		30,588,000,000
Amortized cost basis	33,000,000	46,000,000
Commercial | Principal forgiveness
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	0	0
Commercial | Payment deferral
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	0	0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	13,578,000,000		13,371,000,000
Amortized cost basis	84,000,000	49,000,000
Commercial real estate | Principal forgiveness
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	0	0
Commercial real estate | Payment deferral
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	0	0
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	14,052,000,000		13,820,000,000
Amortized cost basis	6,000,000	2,000,000
Consumer | Principal forgiveness
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	2,000,000	0
Consumer | Payment deferral
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	0	0
Land Acquisition and Development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	237,000,000		219,000,000
Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	16,519,000,000		16,684,000,000
Amortized cost basis	30,000,000	36,000,000
Commercial and industrial | Commercial | Nonaccrual
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	110,000,000		$ 82,000,000
Commercial and industrial | Commercial | Principal forgiveness
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	0	0
Commercial and industrial | Commercial | Payment deferral
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis	$ 0	$ 0