Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)/Income	Treasury Stock
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	12,835			12,835
Other comprehensive income (loss), net of tax	3,805				3,805
Cash dividends declared	(5,357)			(5,357)
Common stock issued in acquisition	142,469	12,333	130,136
Treasury stock issued for restricted awards	(79)			(1,963)		1,884
Recognition of restricted stock compensation expense	319		319
Issuance costs	(123)		(123)
Balance at Mar. 31, 2015	762,258	90,326	209,150	509,575	(10,028)	(36,765)
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	16,093			16,093
Other comprehensive income (loss), net of tax	8,341				8,341
Cash dividends declared	(6,601)			(6,601)
Treasury stock issued for restricted awards	0			(2,491)		2,491
Recognition of restricted stock compensation expense	731		731
Balance at Mar. 31, 2016	$ 810,801	$ 90,326	$ 211,276	$ 551,229	$ (8,116)	$ (33,914)