Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Deferred Benefits for Directors [Member]
Beginning Balance at Dec. 31, 2013	$ 746,595	$ 61,182	$ 244,974	$ 460,351	$ (5,969)	$ (12,734)	$ (1,209)
Beginning Balance, shares at Dec. 31, 2013		29,175,236
Net income	35,296			35,296
Other comprehensive income	7,341					7,341
Comprehensive income	42,637
Common dividends declared ($0.46 and $0.44 per share in June 30, 2015 and 2014 respectively)	(12,861)			(12,861)
Treasury shares acquired	(20)		49		(69)
Treasury shares acquired, shares		(2,258)
Stock options exercised	1,658		(311)		1,969
Stock options exercised, shares		63,393
Restricted stock granted			(1,321)		1,321
Restricted stock granted, shares		42,554
Stock compensation expense	616		616
Deferred benefits for directors- net			22				(22)
Ending Balance at Jun. 30, 2014	778,625	$ 61,182	244,029	482,786	(2,748)	(5,393)	(1,231)
Ending Balance, shares at Jun. 30, 2014		29,278,925
Beginning Balance at Dec. 31, 2014	788,190	$ 61,182	244,661	504,578	(2,151)	(18,825)	(1,255)
Beginning Balance, shares at Dec. 31, 2014		29,298,188
Net income	35,512			35,512
Other comprehensive income	(2,877)					(2,877)
Comprehensive income	32,635
Common dividends declared ($0.46 and $0.44 per share in June 30, 2015 and 2014 respectively)	(17,702)			(17,702)
Shares issued for acquisition	293,629	$ 19,122	274,507
Shares issued for acquisition, shares		9,178,531
Treasury shares acquired	(1,638)				(1,638)
Treasury shares acquired, shares		(50,224)
Stock options exercised	1,173		(223)		1,396
Stock options exercised, shares		44,125
Restricted stock granted			(1,526)		1,526
Restricted stock granted, shares		48,550
Repurchase of stock warrant	(2,247)		(2,247)
Stock compensation expense	613		613
Deferred benefits for directors- net			1,205				(1,205)
Ending Balance at Jun. 30, 2015	$ 1,094,653	$ 80,304	$ 516,990	$ 522,388	$ (867)	$ (21,702)	$ (2,460)
Ending Balance, shares at Jun. 30, 2015		38,519,170