Earnings Per Share (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Distributed earnings allocated to common stock	$ 16,563	$ 16,027	$ 15,524
Undistributed earnings allocated to common stock	37,673	32,923	32,025
Net earnings allocated to common stock	54,236	48,950	47,549
Net earnings allocated to participating securities	722	683	646
Net income available to common shareholders	$ 54,958	$ 49,633	$ 48,195
Weighted average shares outstanding for basic earnings per common share	24,344,623	24,267,471	24,237,924
Dilutive effect of stock compensation (in shares)	586	9,857	9,532
Weighted average shares outstanding for diluted earnings per common share	24,345,209	24,277,328	24,247,456
Basic earnings per common share (in dollars per share)	$ 2.23	$ 2.02	$ 1.96
Diluted earnings per common share (in dollars per share)	$ 2.23	$ 2.02	$ 1.96