Income Per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Per Share of Common Stock
Net income for basic and diluted income per common share	$ 2,559	$ 5,718	$ 4,924	$ 10,210
Weighted-average shares for basic income per share	5,599,000	5,578,000	5,598,000	5,577,000
Effect of dilutive securities:
Employee and director stock options (in shares)	6,000	11,000	7,000	11,000
Adjusted weighted-average shares and assumed exercises for diluted income per share	5,605,000	5,589,000	5,605,000	5,588,000
Basic net income per common share (in dollars per share)	$ 0.46	$ 1.03	$ 0.88	$ 1.83
Diluted net income per common share (in dollars per share)	$ 0.46	$ 1.02	$ 0.88	$ 1.83
Options
Anti-dilutive securities
Anti-dilutive shares of common stock excluded from the calculation of dilutive securities			15,800	15,000