Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Outstanding stock options (in shares)	0	0
Distributed earnings allocated to common stock	$ 4,663	$ 4,686
Undistributed earnings allocated to common stock	11,422	9,017
Net earnings allocated to common stock	16,085	13,703
Net earnings allocated to participating securities	121	115
Net income allocated to common stock and participating securities	$ 16,206	$ 13,818
Weighted average shares outstanding for basic earnings per common share	25,903,397	25,923,530
Dilutive effect of stock compensation (in shares)	0	0
Weighted average shares outstanding for diluted earnings per common share	25,903,397	25,923,530
Basic earnings per common share (in dollars per share)	$ 0.62	$ 0.53
Diluted earnings per common share (in dollars per share)	$ 0.62	$ 0.53