Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic
Net income	$ 6,073	$ 5,962	$ 12,105	$ 11,870
Weighted-average common shares outstanding	11,428,984	11,364,057	11,425,525	11,366,639
Basic earnings per share	$ 0.53	$ 0.53	$ 1.06	$ 1.05
Diluted
Net Income	$ 6,073	$ 5,962	$ 12,105	$ 11,870
Weighted-average common shares outstanding	11,428,984	11,364,057	11,425,525	11,366,639
Effect of dilutive restricted stock, stock options and stock appreciation rights	187,403	183,763	181,169	179,679
Weighted-average common shares outstanding assuming dilution	11,616,387	11,547,820	11,606,694	11,546,318
Diluted earnings per share	$ 0.52	$ 0.52	$ 1.04	$ 1.03