Loans and Leases (Troubled Debt Restructurings) (Details) - Lease Financing, net $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	23	19	61	74
Recorded Investment	$ 8.0	$ 7.8	$ 21.3	$ 29.7
Unpaid Principal Balance	$ 9.3	$ 8.1	$ 23.0	$ 35.4
Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	2	2	3	12
Recorded Investment	$ 0.0	$ 1.5	$ 1.3	$ 12.8
Unpaid Principal Balance	$ 1.0	$ 1.5	$ 2.3	$ 17.2
Commercial | Commercial and Institutional
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	2	1	2	5
Recorded Investment	$ 0.0	$ 0.1	$ 0.0	$ 4.1
Unpaid Principal Balance	$ 1.0	$ 0.1	$ 1.0	$ 6.2
Commercial | Real Estate
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	0	1	1	7
Recorded Investment	$ 0.0	$ 1.4	$ 1.3	$ 8.7
Unpaid Principal Balance	$ 0.0	$ 1.4	$ 1.3	$ 11.0
Personal
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	21	17	58	62
Recorded Investment	$ 8.0	$ 6.3	$ 20.0	$ 16.9
Unpaid Principal Balance	$ 8.3	$ 6.6	$ 20.7	$ 18.2
Personal | Real Estate
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	21	16	57	60
Recorded Investment	$ 8.0	$ 6.2	$ 20.0	$ 14.8
Unpaid Principal Balance	$ 8.3	$ 6.5	$ 20.6	$ 16.1
Personal | Private Client
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | Contract	0	1	1	2
Recorded Investment	$ 0.0	$ 0.1	$ 0.0	$ 2.1
Unpaid Principal Balance	$ 0.0	$ 0.1	$ 0.1	$ 2.1