Loans And Allowance For Credit Losses (Summary Of Nonaccrual Loans) (Details) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Total	[1]	$ 265	$ 381
loans held for sale [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		13	40
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		6	7
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		1	0
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		8	14
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		85	74
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		1	1
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		351	443
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		41	29
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		47	36
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		11	11
One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		40	36
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		1	2
Revolving Credit Facility [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		1	1
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		54	50
Financing Receivables, Total [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		452	529
Commercial and Industrial Sector [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total		$ 257	$ 354

[1] 1 Represents nonaccrual loans that are not past due more than 30 days; however, full payment of principal and interest is still not expected.