Loans, Leases, and Allowance for Credit Losses (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Financing Receivable, Allowance for Credit Losses [Line Items]
Net unamortized purchase premiums, discounts, and deferred loan fees and cost	$ 44,000,000		$ 44,000,000		$ 83,000,000
Accrued interest receivable	196,000,000		196,000,000		161,000,000
Total loans	53,918,000,000		53,918,000,000		50,851,000,000
Loans held for sale	25,000,000		25,000,000		83,000,000
Held-for-sale loans sold	112,000,000	$ 400,000,000	635,000,000	$ 1,200,000,000
Payments for origination and purchases of loans held-for-sale	96,000,000	400,000,000	583,000,000	1,200,000,000
Principal balance of loans sold, serviced loans	3,500,000,000		3,500,000,000		3,300,000,000
Total income from loans sold	2,000,000	12,000,000	12,000,000	30,000,000
Loans and leases, net of unearned income and fees	53,918,000,000		53,918,000,000		50,851,000,000
Financing receivable, commitments threshold for evaluating collectively or individually	1,000,000		1,000,000
Total allowance for credit losses	590,000,000	529,000,000	590,000,000	529,000,000
Unfunded lending commitments on troubled debt restructuring	6,000,000		6,000,000		10,000,000
Amortized cost of TDR loans modified with interest rates below market			245,000,000		326,000,000
Financing receivable, modifications, subsequent default, recorded investment	13,000,000	2,000,000	13,000,000	5,000,000
Real estate acquired through foreclosure	0		0		0
Mortgage loans in process of foreclosure	11,000,000		11,000,000		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		27,600,000,000		26,800,000,000
Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost of TDR loans modified with interest rates below market			39,000,000		105,000,000
Doubtful
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and leases, net of unearned income and fees	1,000,000		1,000,000		0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	12,356,000,000		12,356,000,000		12,198,000,000
Total allowance for credit losses	153,000,000	111,000,000	153,000,000	111,000,000
Commercial real estate | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost of TDR loans modified with interest rates below market			15,000,000		16,000,000
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	11,750,000,000		11,750,000,000		10,213,000,000
Total allowance for credit losses	125,000,000	100,000,000	125,000,000	100,000,000
Consumer | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost of TDR loans modified with interest rates below market			7,000,000		5,000,000
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	29,812,000,000		29,812,000,000		28,440,000,000
Total allowance for credit losses	312,000,000	$ 318,000,000	312,000,000	$ 318,000,000
Commercial | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost of TDR loans modified with interest rates below market			17,000,000		84,000,000
Interest Rate Below Market, Including Multiple Modification Types
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost of TDR loans modified with interest rates below market			60,000,000		100,000,000
Land Acquisition and Development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	257,000,000		257,000,000		160,000,000
Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 15,656,000,000		15,656,000,000		13,867,000,000
Commercial and industrial | Commercial | Nonaccruing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost of TDR loans modified with interest rates below market			$ 9,000,000		$ 64,000,000