Loans, Credit Risk Profile Based on Rating Category and Payment Activity and on Performing and Nonperforming Status, Segregated by Class (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		$ 3,087,342	$ 2,938,371
Consumer mortgage loans secured by real estate properties for which formal foreclosure proceedings are in process		5,000	3,500
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		1,608,359	1,508,097
Commercial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		$ 1,426,421	1,335,205
Commercial [Member] | Pass [Member] | Minimum [Member]
Financing Receivable, Recorded Investment [Line Items]
Review period for loans		12 months
Commercial [Member] | Pass [Member] | Maximum [Member]
Financing Receivable, Recorded Investment [Line Items]
Review period for loans		18 months
Commercial [Member] | Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		$ 99,443	88,215
Commercial [Member] | OAEM [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		34,213	36,389
Commercial [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		47,382	47,136
Commercial [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		900	1,152
Commercial [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		72,054	66,998
Commercial [Member] | Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		62,033	55,315
Commercial [Member] | Construction [Member] | Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		3,988	3,366
Commercial [Member] | Construction [Member] | OAEM [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		1,874	2,535
Commercial [Member] | Construction [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		3,981	5,592
Commercial [Member] | Construction [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		178	190
Commercial [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		1,179,229	1,085,428
Commercial [Member] | Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		1,056,938	975,383
Commercial [Member] | Real Estate [Member] | Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		64,594	51,932
Commercial [Member] | Real Estate [Member] | OAEM [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		23,458	25,772
Commercial [Member] | Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		33,882	31,945
Commercial [Member] | Real Estate [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		357	396
Commercial [Member] | Equipment Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		4,903	5,512
Commercial [Member] | Equipment Leases [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		4,667	5,206
Commercial [Member] | Equipment Leases [Member] | Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		0	137
Commercial [Member] | Equipment Leases [Member] | OAEM [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		106	169
Commercial [Member] | Equipment Leases [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		130	0
Commercial [Member] | Equipment Leases [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		0	0
Commercial [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		352,173	350,159
Commercial [Member] | Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		302,783	299,301
Commercial [Member] | Other [Member] | Watch [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		30,861	32,780
Commercial [Member] | Other [Member] | OAEM [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		8,775	7,913
Commercial [Member] | Other [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		9,389	9,599
Commercial [Member] | Other [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		365	566
Residential [Member] | Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		58,566	57,966
Residential [Member] | Construction [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		58,172	57,803
Residential [Member] | Construction [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile	[1]	394	163
Residential [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		708,467	702,969
Residential [Member] | Real Estate [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		695,964	690,414
Residential [Member] | Real Estate [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile	[1]	12,503	12,555
Residential [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		93,721	91,511
Residential [Member] | Home Equity [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		92,865	90,489
Residential [Member] | Home Equity [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile	[1]	856	1,022
Consumer [Member] | Consumer Direct [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		135,228	133,093
Consumer [Member] | Consumer Direct [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		135,194	133,025
Consumer [Member] | Consumer Direct [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile	[1]	34	68
Consumer [Member] | Consumer Indirect [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		483,001	444,735
Consumer [Member] | Consumer Indirect [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		482,780	444,054
Consumer [Member] | Consumer Indirect [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile	[1]	221	681
Residential and Consumer Portfolio Segments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		1,478,983	1,430,274
Residential and Consumer Portfolio Segments [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile		1,464,975	1,415,785
Residential and Consumer Portfolio Segments [Member] | Nonperforming [Member]
Financing Receivable, Recorded Investment [Line Items]
Loan portfolio based on credit risk profile	[1]	$ 14,008	$ 14,489

[1] A loan is considered nonperforming if it is 90 days or more past due and/or on nonaccrual.