Loans, Leases, And Allowance For Credit Losses (Summary Of Major Portfolio Segment And Specific Loan Class) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	$ 89	$ 129
Total loans and leases	54,745	48,709
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	31,514	25,388
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	13,543	14,760
Commercial | PPP
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	6,810	0
Commercial | Leasing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	319	334
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	8,136	7,901
Commercial | Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,706	2,393
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	12,027	11,555
Commercial real estate | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,298	2,211
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	9,729	9,344
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	11,204	11,766
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,797	2,917
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	7,209	7,568
Consumer | Construction and other consumer real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	633	624
Consumer | Bankcard and other revolving plans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	431	502
Consumer | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 134	$ 155