Earnings Per Share (Details 2) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Distributed earnings allocated to common stock		$ 17,582	$ 17,091	$ 16,563
Undistributed earnings allocated to common stock		39,336	40,249	37,673
Net earnings allocated to common stock		56,918	57,340	54,236
Net earnings allocated to participating securities		568	729	722
Net income available to common shareholders		$ 57,486	$ 58,069	$ 54,958
Weighted average shares outstanding for basic earnings per common share	[1]	26,173,351	26,434,769	26,779,086
Dilutive effect of stock compensation (in shares)	[1]	0	0	644
Weighted average shares outstanding for diluted earnings per common share	[1]	26,173,351	26,434,769	26,779,730
Basic earnings per common share (in dollars per share)	[2]	$ 2.17	$ 2.17	$ 2.03
Diluted earnings per common share (in dollars per share)	[2]	$ 2.17	$ 2.17	$ 2.03

[1] *Share and per share data gives retrospective recognition to a 10% stock dividend declared on July 22, 2015 and issued on August 14, 2015.

[2] *The computation of basic and diluted net income per common share gives retrospective recognition to a 10% stock dividend declared on July 22, 2015 and issued on August 14, 2015.