Allowance for Loan and Lease Loss and Credit Quality (Narrative) (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) risk_code	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) risk_code	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for loan and lease losses, subsequent deterioration of purchased impaired loans | $	$ 96,000	$ 1,400,000	$ 96,000	$ 1,400,000
Allowance For Loan And Lease Losses, Purchased Impaired Loans, Period Increase (Decrease) | $	133,000	71,000	214,000	847,000
Financing receivables modified as troubled debt restructurings within the previous 12 months for which there was a payment default | $	0	$ 227,000	$ 118,000	$ 227,000
Homogeneous | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Duration of time account is past due before risk rating is applied			30 days
Restructured Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired loans | $	$ 52,900,000		$ 52,900,000		$ 40,700,000
Percentage of loan collateral balance			100.00%
Available commitments for troubled debt restructurings outstanding | $			$ 0		$ 0
Minimal Risk | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	1		1
Loss | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	10		10
Loss | Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	10		10
Loss | Homogeneous | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			180 days
Loss | Homogeneous Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	10		10
Loss | Homogeneous Retail | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			120 days
Loss | Homogeneous Retail | Minimum | Open-End Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			180 days
Loss | Homogeneous Retail | Minimum | Closed-End Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			120 days
Low Risk | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	2		2
Modest Risk | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	3		3
Average Risk | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	4		4
Acceptable Risk | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	5		5
Pass/Watch | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	6		6
Special Mention | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	7		7
Special Mention | Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	7		7
Special Mention | Homogeneous | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			30 days
Special Mention | Homogeneous | Maximum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			59 days
Special Mention | Homogeneous Retail | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			30 days
Special Mention | Homogeneous Retail | Maximum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			89 days
Substandard | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	8		8
Substandard | Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	8		8
Substandard | Homogeneous | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			60 days
Substandard | Homogeneous | Maximum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			89 days
Substandard | Homogeneous Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	8		8
Substandard | Homogeneous Retail | Minimum | Open-End Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			90 days
Substandard | Homogeneous Retail | Minimum | Closed-End Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			90 days
Substandard | Homogeneous Retail | Maximum | Open-End Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			180 days
Substandard | Homogeneous Retail | Maximum | Closed-End Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			120 days
Doubtful | Non-Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	9		9
Doubtful | Homogeneous
Financing Receivable, Allowance for Credit Losses [Line Items]
Internal risk rating code	9		9
Doubtful | Homogeneous | Minimum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			90 days
Doubtful | Homogeneous | Maximum
Financing Receivable, Allowance for Credit Losses [Line Items]
Days past due on account for qualifying credit quality indicator			179 days