Loans (Schedule Of Loans By Segment, Based On Obligor Location) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 29,113.9	$ 29,535.9	$ 30,518.7
Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	23,159.3	22,562.3
Consumer Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	5,954.6	6,973.6
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	27,323.3	27,414.3
Domestic | Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	21,368.7	20,440.7
Domestic | Consumer Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	5,954.6	6,973.6
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,790.6	2,121.6
Foreign | Commercial Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,790.6	2,121.6
Foreign | Consumer Banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 0.0	$ 0.0