Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
BASIC
Net income	$ 8,375	$ 8,488	$ 13,564	$ 12,761
Weighted-average common shares outstanding (in shares)	15,732	15,784	15,819	15,785
Basic earnings per share (in dollars per share)	$ 0.53	$ 0.54	$ 0.86	$ 0.81
DILUTED
Net income	$ 8,375	$ 8,488	$ 13,564	$ 12,761
Weighted-average common shares outstanding (in shares)	15,732	15,784	15,819	15,785
Dilutive effect of stock options and restricted stock (in shares)	297	357	317	366
Weighted-average common shares outstanding on a diluted basis (in shares)	16,029	16,141	16,136	16,151
Diluted earnings per share (in dollars per share)	$ 0.52	$ 0.53	$ 0.84	$ 0.79