Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2013	$ 571,306	$ 77,993	$ 78,140	$ 468,158	$ (12,694)	$ (40,291)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	57,910			57,910
Other comprehensive income (loss), net of tax	(1,139)				(1,139)
Cash dividends declared	(20,203)			(20,203)
Treasury stock issued	(163)			(1,805)		1,642
Recognition of restricted stock compensation expense	933		933
Tax benefit from stock-based compensation	16		16
Issuance costs	(271)		(271)
Ending balance at Dec. 31, 2014	608,389	77,993	78,818	504,060	(13,833)	(38,649)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	67,081			67,081
Other comprehensive income (loss), net of tax	(2,624)				(2,624)
Cash dividends declared	(24,487)			(24,487)
Common stock issued in acquisition	142,469	12,333	130,136
Treasury stock issued	(182)			(2,426)		2,244
Recognition of restricted stock compensation expense	1,670		1,670
Tax benefit from stock-based compensation	53		53
Issuance costs	(132)		(132)
Ending balance at Dec. 31, 2015	792,237	90,326	210,545	544,228	(16,457)	(36,405)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	71,392			71,392
Other comprehensive income (loss), net of tax	2,673				2,673
Cash dividends declared	(26,784)			(26,784)
Treasury stock issued	(115)			(2,945)		2,830
Recognition of restricted stock compensation expense	2,544		2,544	0		0
Tax benefit from stock-based compensation	9		9
Ending balance at Dec. 31, 2016	$ 841,956	$ 90,326	$ 213,098	$ 585,891	$ (13,784)	$ (33,575)