Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, except Share data	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, 2011	$ 633,790	$ 55,487	$ 191,679	$ 388,818	$ (96)	$ (902)	$ (1,196)
Beginning Balance, shares at Dec. 31, 2011		26,629,360
Net income	23,988			23,988
Other comprehensive income	59					59
Comprehensive income	24,047
Common dividends declared	(9,060)			(9,060)
Treasury shares acquired	(70)		22		(92)
Treasury shares acquired, shares		(4,766)
Restricted stock granted		71	(198)		127
Restricted stock granted, shares		40,050
Stock compensation expense	405		405
Deferred benefits for directors- net			18				(18)
Ending Balance at Jun. 30, 2012	649,112	55,558	191,926	403,746	(61)	(843)	(1,214)
Ending Balance, shares at Jun. 30, 2012		26,664,644
Beginning Balance at Dec. 31, 2012	714,184	60,863	241,672	419,246		(6,365)	(1,232)
Beginning Balance, shares at Dec. 31, 2012		29,214,660
Net income	33,037			33,037
Other comprehensive income	(10,964)					(10,964)
Comprehensive income	22,073
Common dividends declared	(11,115)			(11,115)
Treasury shares acquired	(296)				(296)
Treasury shares acquired, shares		(11,851)
Stock options exercised	1,018	94	897		27
Stock options exercised, shares		46,025
Restricted stock granted		57	(326)		269
Restricted stock granted, shares		38,250
Adjustment to shares issued in acquisition	(104)	(9)	(95)
Adjustment to shares issued in acquisition, shares		(4,672)
Stock compensation expense	472		472
Deferred benefits for directors- net			20				(20)
Ending Balance at Jun. 30, 2013	$ 726,232	$ 61,005	$ 242,640	$ 441,168		$ (17,329)	$ (1,252)
Ending Balance, shares at Jun. 30, 2013		29,282,412