Loans, Nonaccrual Loans Segregated by Class of Loans and Loan Portfolio Aging Analysis, Segregated by Class (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		$ 13,032	$ 18,119
Total Past Due		47,705	45,403
Current		3,130,183	3,077,537
Total Loans		3,177,888	3,122,940
90+ and Accruing	[1]	8,005	10,176
Minimum threshold amount of loans requiring performance bond		500
30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		14,147	13,401
60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		15,449	8,632
90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		$ 18,109	23,370
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		$ 1,613,735	1,619,235
Commercial [Member] | Construction [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		619	1,207
Total Past Due		794	1,376
Current		80,678	75,103
Total Loans		81,472	76,479
90+ and Accruing	[1]	47	31
Commercial [Member] | Construction [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		127	138
Commercial [Member] | Construction [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		116	0
Commercial [Member] | Construction [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		551	1,238
Commercial [Member] | Real Estate [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		5,061	7,028
Total Past Due		20,809	14,160
Current		1,162,823	1,174,520
Total Loans		1,183,632	1,188,680
90+ and Accruing	[1]	2,453	2,665
Commercial [Member] | Real Estate [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		5,962	4,047
Commercial [Member] | Real Estate [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		8,174	1,599
Commercial [Member] | Real Estate [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		6,673	8,514
Commercial [Member] | Equipment Lease Financing [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		0	430
Current		1,986	2,612
Total Loans		1,986	3,042
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	430
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]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		443	934
Total Past Due		1,630	1,564
Current		345,015	349,470
Total Loans		346,645	351,034
90+ and Accruing	[1]	90	87
Commercial [Member] | Other [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		549	835
Commercial [Member] | Other [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		794	77
Commercial [Member] | Other [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		287	652
Residential [Member] | Construction [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		22	318
Total Past Due		671	649
Current		61,111	66,709
Total Loans		61,782	67,358
90+ and Accruing	[1]	11	223
Residential [Member] | Construction [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		420	224
Residential [Member] | Construction [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		218	202
Residential [Member] | Construction [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		33	223
Residential [Member] | Real Estate [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		6,401	8,243
Total Past Due		14,888	18,698
Current		707,134	690,872
Total Loans		722,022	709,570
90+ and Accruing	[1]	4,413	6,293
Residential [Member] | Real Estate [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		939	2,064
Residential [Member] | Real Estate [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		4,658	5,029
Residential [Member] | Real Estate [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		9,291	11,605
Residential [Member] | Home Equity [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Nonaccrual loans segregated by class of loans		486	389
Total Past Due		1,803	1,201
Current		102,002	98,155
Total Loans		103,805	99,356
90+ and Accruing	[1]	310	167
Residential [Member] | Home Equity [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		917	595
Residential [Member] | Home Equity [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		293	178
Residential [Member] | Home Equity [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		593	428
Consumer [Member] | Consumer Direct [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		1,219	1,193
Current		144,783	136,561
Total Loans		146,002	137,754
90+ and Accruing	[1]	36	62
Consumer [Member] | Consumer Direct [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		828	983
Consumer [Member] | Consumer Direct [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		355	148
Consumer [Member] | Consumer Direct [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		36	62
Consumer [Member] | Consumer Indirect [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		5,891	6,132
Current		524,651	483,535
Total Loans		530,542	489,667
90+ and Accruing	[1]	645	648
Consumer [Member] | Consumer Indirect [Member] | 30-59 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		4,405	4,085
Consumer [Member] | Consumer Indirect [Member] | 60-89 Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		841	1,399
Consumer [Member] | Consumer Indirect [Member] | 90+ Days Past Due [Member]
Bank's Loan portfolio aging analysis, segregated by class [Abstract]
Total Past Due		$ 645	$ 648

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