Net Income Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Summary of net income per share
Net income	$ 3,714		$ 3,785
Weighted-average common shares outstanding	17,312		17,152
Basic earnings per share	$ 0.21	[1]	$ 0.22	[1]
Weighted-average common shares outstanding	17,312,614	[1]	17,152,130	[1]
Common stock equivalents due to effect of stock options	154		176
Total weighted-average common shares and equivalents	17,466		17,328
Diluted earnings per share	$ 0.21	[1]	$ 0.22	[1]

[1] Outstanding shares and per share data have been adjusted to reflect the six-for-five stock split declared April 16, 2013.