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, 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 (loss)	(10,964)					(10,964)
Comprehensive income	22,073
Common dividends declared (0.44 and 0.38 per share in June 30, 2014 and 2013 respectively)	(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	0	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	0		20				(20)
Ending Balance at Jun. 30, 2013	726,232	61,005	242,640	441,168	0	(17,329)	(1,252)
Ending Balance, Shares at Jun. 30, 2013		29,282,412
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 (loss)	7,341					7,341
Comprehensive income	42,637
Common dividends declared (0.44 and 0.38 per share in June 30, 2014 and 2013 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	0		(1,321)		1,321
Restricted stock granted, Shares		42,554
Stock compensation expense	616		616
Deferred benefits for directors- net	0		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