Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Distributed earnings allocated to common stock	$ 5,748	$ 5,118
Undistributed earnings allocated to common stock	2,175	4,837
Net earnings allocated to common shareholders	$ 7,923	$ 9,955
Average common shares outstanding	15,473	14,679
Effect of dilutive securities, Warrants outstanding	55
Effect of dilutive securities, Employee stock options	99	80
Shares for diluted earnings per share	15,627	14,759
Basic earnings per share	$ 0.51	$ 0.68
Diluted earnings per share	$ 0.51	$ 0.67
Options to purchase shares of common stock, anti-dilutive	10,000	109,400
Common stock exercise price	$ 40.88
Common stock exercise price, lower limit		$ 35.39
Common stock exercise price, upper limit		$ 40.88