Summary of Significant Accounting Policies (VIEs, Receivables and loans, Cash Equivalents) (Details 1) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) class segment component	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Unfunded commitments to fund low-income housing partnerships	$ 17,453
Loans and Leases
Number of portfolio segments of loans and leases (commercial and consumer) | segment	2
Number of classes of loans and leases determined by management | class	8
Loans modified in a troubled debt restructuring
Period during which non-accrual loan that has been modified in a troubled debt restructuring remains on non-accrual status (in months)	6 months
Number of components of company's reserve for credit losses | component	2
Cash and Cash Equivalents
Maximum original maturity period of cash and cash equivalents (in days)	90 days
Low-income housing partnerships
Variable Interest Entity [Line Items]
Period over which tax credits or benefits are generally recognized (in years)	10 years
Solar energy partnerships
Variable Interest Entity [Line Items]
Period over which tax credits or benefits are generally recognized (in years)	6 years
Commercial
Non-Performing Loans and Leases
Minimum maturity period to be considered to place loans and leases on non-accrual status (in days)	90 days
Residential mortgage and home equity loan
Non-Performing Loans and Leases
Minimum maturity period to be considered to place loans and leases on non-accrual status (in days)	120 days
Home Equity
Non-Performing Loans and Leases
Minimum maturity period to be considered for loans and leases to be charged off (in days)	120 days
Home Equity | Maximum
Non-Performing Loans and Leases
Combined loan-to-value ratio, considered in determining whether the entire outstanding balance on the loan is to be charged-off or not (as a percent)	60.00%
Automobile and Other consumer
Non-Performing Loans and Leases
Minimum maturity period to be considered for loans and leases to be charged off (in days)	120 days
Credit Cards
Non-Performing Loans and Leases
Minimum maturity period to be considered for loans and leases to be charged off (in days)	180 days
Commercial and Industrial
Non-Performing Loans and Leases
Minimum maturity period to be considered for loans and leases to be charged off (in days)	120 days
Other Assets
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	$ 87,600	$ 78,900
Other Liabilities
Variable Interest Entity [Line Items]
Unfunded commitments to fund low-income housing partnerships	$ 17,500	$ 16,200