Summary of Significant Accounting Policies (Details 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income	$ 3,697	$ 3,112	$ 4,474	$ 2,131	$ 4,443	$ 3,245	$ 4,777	$ 2,439	$ 13,414	$ 14,904	$ 15,273
Less: Net income allocated to unvested participating securities									250	234	135
Net income available to common stockholders									$ 13,164	$ 14,670	$ 15,138
Denominator:
Denominator for basic earnings per share-weighted average shares	5,732	5,724	5,712	5,710	5,709	5,699	5,699	5,690	5,706	5,700	5,681
Effect of dilutive securities:
Stock options									34	53	64
Denominator for diluted earnings per share - adjusted weighted-average shares and assumed conversions	5,741	5,752	5,757	5,762	5,757	5,742	5,754	5,757	5,740	5,753	5,745
Basic earnings per share	$ 0.63	$ 0.54	$ 0.77	$ 0.37	$ 0.77	$ 0.56	$ 0.83	$ 0.43	$ 2.31	$ 2.57	$ 2.66
Diluted earnings per share	$ 0.63	$ 0.53	$ 0.77	$ 0.36	$ 0.76	$ 0.56	$ 0.82	$ 0.42	$ 2.29	$ 2.55	$ 2.64