Loans, Nonaccrual Loans Segregated by Class of Loans and Loan Portfolio Aging Analysis, Segregated by Class (Details) - USD ($)		9 Months Ended
		Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		$ 16,798,000	$ 16,563,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		44,864,000	40,279,000
Current		2,886,435,000	2,833,682,000
Total Loans		2,931,299,000	2,873,961,000
90+ and Accruing	[1]	11,498,000	12,046,000
Minimum threshold amount of loans requiring performance bond		500,000
30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		11,575,000	9,010,000
60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		10,681,000	6,140,000
90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		$ 22,608,000	25,129,000
Equipment Lease Financing [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Financing percentage requested for underwriting loans		100.00%
Commercial [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Loans		$ 1,513,141,000	1,498,351,000
Commercial [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		2,216,000	3,402,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		2,256,000	3,473,000
Current		66,019,000	74,547,000
Total Loans		68,275,000	78,020,000
90+ and Accruing	[1]	24,000	30,000
Commercial [Member] | Construction [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		41,000	36,000
Commercial [Member] | Construction [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		0	6,000
Commercial [Member] | Construction [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		2,215,000	3,431,000
Commercial [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		7,328,000	5,928,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		15,766,000	11,492,000
Current		1,067,874,000	1,041,427,000
Total Loans		1,083,640,000	1,052,919,000
90+ and Accruing	[1]	5,001,000	3,757,000
Commercial [Member] | Real Estate [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		3,720,000	2,947,000
Commercial [Member] | Real Estate [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		2,850,000	622,000
Commercial [Member] | Real Estate [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		9,196,000	7,923,000
Commercial [Member] | Equipment Lease Financing [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		0	199,000
Current		6,242,000	8,315,000
Total Loans		6,242,000	8,514,000
90+ and Accruing	[1]	0	0
Commercial [Member] | Equipment Lease Financing [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		0	199,000
Commercial [Member] | Equipment Lease Financing [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		0	0
Commercial [Member] | Equipment Lease Financing [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		0	0
Commercial [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		1,446,000	1,485,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		2,796,000	2,359,000
Current		352,188,000	356,539,000
Total Loans		354,984,000	358,898,000
90+ and Accruing	[1]	345,000	310,000
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		1,277,000	762,000
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		236,000	121,000
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		1,283,000	1,476,000
Residential [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		11,000	249,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		2,150,000	796,000
Current		53,262,000	60,954,000
Total Loans		55,412,000	61,750,000
90+ and Accruing	[1]	478,000	55,000
Residential [Member] | Construction [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		1,386,000	443,000
Residential [Member] | Construction [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		286,000	62,000
Residential [Member] | Construction [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		478,000	291,000
Residential [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		5,475,000	5,206,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		15,028,000	15,923,000
Current		691,000,000	691,951,000
Total Loans		706,028,000	707,874,000
90+ and Accruing	[1]	4,819,000	6,925,000
Residential [Member] | Real Estate [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		897,000	1,128,000
Residential [Member] | Real Estate [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		5,762,000	3,888,000
Residential [Member] | Real Estate [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		8,369,000	10,907,000
Residential [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		322,000	183,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		1,908,000	1,255,000
Current		87,559,000	88,195,000
Total Loans		89,467,000	89,450,000
90+ and Accruing	[1]	405,000	448,000
Residential [Member] | Home Equity [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		947,000	527,000
Residential [Member] | Home Equity [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		320,000	148,000
Residential [Member] | Home Equity [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		641,000	580,000
Consumer [Member] | Consumer Direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans segregated by class of loans		0	110,000
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		1,260,000	1,440,000
Current		130,555,000	124,966,000
Total Loans		131,815,000	126,406,000
90+ and Accruing	[1]	109,000	126,000
Consumer [Member] | Consumer Direct [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		901,000	835,000
Consumer [Member] | Consumer Direct [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		250,000	479,000
Consumer [Member] | Consumer Direct [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		109,000	126,000
Consumer [Member] | Consumer Indirect [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		3,700,000	3,342,000
Current		431,736,000	386,788,000
Total Loans		435,436,000	390,130,000
90+ and Accruing	[1]	317,000	395,000
Consumer [Member] | Consumer Indirect [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		2,406,000	2,133,000
Consumer [Member] | Consumer Indirect [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		977,000	814,000
Consumer [Member] | Consumer Indirect [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		$ 317,000	$ 395,000

[1] 90+ and Accruing are also included in 90+ Days Past Due column.