Income Taxes - Income Tax Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amounts
Income tax computed at federal statutory rates	$ 5,977	$ 7,389	$ 8,410
Tax effect of exclusion of interest income on obligations of states and political subdivisions (in Dollars)	(1,546)	(1,600)	(1,631)
Reduction of interest expense incurred to carry tax-exempt assets	42	59	78
State income taxes, net of federal tax benefit	532	938	1,133
Nondeductible expenses primarily related to the acquisition of CVBK		251
Tax credits	(180)	(225)	(225)
Other	(95)	(102)	(119)
Income tax expense	$ 4,730	$ 6,710	$ 7,646
Percent of Pre-tax Income
Income tax computed at federal statutory rates (as a percent)	35.00%	35.00%	35.00%
Tax effect of exclusion of interest income on obligations of states and political subdivisions (as a percent)	(9.00%)	(7.60%)	(6.80%)
Reduction of interest expense incurred to carry tax-exempt assets (as a percent)	0.30%	0.30%	0.30%
State income taxes, net of federal tax benefit	3.10%	4.40%	4.70%
Nondeductible expenses primarily related to the acquisition of CVBK		1.20%
Tax credits	(1.10%)	(1.10%)	(0.90%)
Other	(0.60%)	(0.40%)	(0.50%)
Income tax expense (as a percent)	27.70%	31.80%	31.80%