Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Outstanding stock options (in shares)		0	0	0	0
Distributed earnings allocated to common stock		$ 4,293	$ 4,362	$ 8,589	$ 8,497
Undistributed earnings allocated to common stock		11,186	9,956	20,249	19,267
Net earnings allocated to common stock		15,479	14,318	28,838	27,764
Net earnings allocated to participating securities		151	176	303	362
Net income allocated to common stock and participating securities		$ 15,630	$ 14,494	$ 29,141	$ 28,126
Weighted average shares outstanding for basic earnings per common share	[1]	26,212,999	26,485,789	26,235,511	26,616,762
Dilutive effect of stock compensation (in shares)		0	0	0	0
Weighted average shares outstanding for diluted earnings per common share	[1]	26,212,999	26,485,789	26,235,511	26,616,762
Basic earnings per common share (in dollars per share)	[1]	$ 0.59	$ 0.54	$ 1.10	$ 1.04
Diluted earnings per common share (in dollars per share)	[1]	$ 0.59	$ 0.54	$ 1.10	$ 1.04

[1] *The computation of per common share data and shares outstanding gives retrospective recognition to a 10% stock dividend declared on July 22, 2015.