Income Per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income per share of common stock:
Net income for basic and diluted income per common share	$ 3,687	$ 2,559	$ 7,753	$ 4,924
Weighted-average shares for basic income per share	5,565,000	5,599,000	5,571,000	5,598,000
Effect of dilutive securities:
Employee and director stock options (in shares)	3,000	6,000	3,000	7,000
Adjusted weighted-average shares and assumed exercises for diluted income per share	5,568,000	5,605,000	5,574,000	5,605,000
Basic net income per common share (in dollars per share)	$ 0.66	$ 0.46	$ 1.39	$ 0.88
Diluted net income per common share (in dollars per share)	$ 0.66	$ 0.46	$ 1.39	$ 0.88
Options
Anti-dilutive securities
Anti-dilutive shares of common stock excluded from the calculation of dilutive securities	32,400	17,400	33,600	17,400