Loans And Allowance For Credit Losses (Summary Of Major Portfolio Segment And Specific Loan Class) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at end of period	$ 541	$ 597	$ 541	$ 597
Loans held for sale	71		71			$ 172
Commercial and industrial	14,041		14,041			13,452
Leasing	343		343			423
Owner occupied	7,082		7,082			6,962
Municipal	1,073		1,073			778
Construction and land development	2,170		2,170			2,019
Term	8,944		8,944			9,322
Provision for loan losses	(5)	(19)	(35)	(95)
Allowance for Loan and Lease Losses, Write-offs	(25)	(54)	(117)	(159)
Allowance for Loan and Lease Losses, Recoveries of Bad Debts	17	24	56	55
Net loan and lease charge-offs	(8)	(30)	(61)	(104)
Reserve for unfunded lending commitments	59	62	59	62	$ 63	65	$ 65	$ 75
Provision for Unfunded Lending Commitments	(4)	(3)	(6)	(13)
Total allowance for credit losses	600	$ 659	600	$ 659
Loans Receivable, Gross, Commercial, Real Estate	11,114		11,114			11,341
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,745		2,745			2,645
Loans and Leases Receivable, Gross, Consumer, Mortgage	6,522		6,522			5,891
Loans and Leases Receivable, Gross, Consumer, Construction	558		558			486
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	490		490			481
Loans and Leases Receivable, Gross, Consumer, Other	188		188			190
Loans and Leases Receivable, Gross	44,156		44,156			42,649
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	22,539		22,539			21,615
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, before Fees, Gross	$ 10,503		$ 10,503			$ 9,693