Income Per Share of Common Stock (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Per Share of Common Stock
Net income for basic and diluted income per common share	$ 4,492	$ 2,757
Weighted-average shares for basic income per common share	5,576	5,558
Effect of dilutive securities:
Employee and director stock options (in shares)	10	10
Adjusted weighted-average shares and assumed exercises for diluted income per share	5,586	5,568
Basic net income per common share (in dollars per share)	$ 0.81	$ 0.50
Diluted net income per common share (in dollars per share)	$ 0.80	$ 0.50
Options
Anti-dilutive securities
Anti-dilutive shares of common stock excluded from the calculation of dilutive securities	15	10