Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]
Outstanding stock options (in shares)	0	0
Distributed earnings allocated to common stock	$ 4,135	$ 4,143
Undistributed earnings allocated to common stock	9,311	8,101
Net earnings allocated to common stock	13,446	12,244
Net earnings allocated to participating securities	186	160
Net income allocated to common stock and participating securities	$ 13,632	$ 12,404
Weighted average shares outstanding for basic earnings per common share	24,317,446	24,321,985
Dilutive effect of stock compensation (in shares)	0	2,343
Weighted average shares outstanding for diluted earnings per common share	24,317,446	24,324,328
Basic earnings per common share (in dollars per share)	$ 0.55	$ 0.50
Diluted earnings per common share (in dollars per share)	$ 0.55	$ 0.50