CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (USD $) In Thousands	Total	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance at Dec. 31, 2011	$ 1,191,132	$ 55,057	$ 723,299	$ 697,923	$ 81,099	$ (366,246)
Total comprehensive income	121,971			101,657	20,314
Cash dividends ($0.615 and $0.645 per share in 2012 and 2013, respectively)	(24,939)			(24,939)
Purchase of treasury stock	(6,062)					(6,062)
Issuance of equity awards	244		(1,612)			1,856
Recognition of equity based compensation	5,425		5,425
Net tax benefit related to equity compensation plans	333		333
Sale of treasury stock	610		354			256
Exercise of stock options	5,461		2,475			2,986
Ending Balance at Sep. 30, 2012	1,294,175	55,057	730,274	774,641	101,413	(367,210)
Beginning Balance at Dec. 31, 2012	1,279,345	55,057	732,069	787,015	85,588	(380,384)
Total comprehensive income	(1,964)			99,302	(101,266)
Cash dividends ($0.615 and $0.645 per share in 2012 and 2013, respectively)	(26,179)			(26,179)
Purchase of treasury stock	(2,551)					(2,551)
Issuance of equity awards	449		(2,189)			2,638
Recognition of equity based compensation	6,319		6,319
Net tax benefit related to equity compensation plans	963		963
Sale of treasury stock	539		367			172
Exercise of stock options	5,557		2,916			2,641
Common stock issuance	201,177		121,708			79,469
Ending Balance at Sep. 30, 2013	$ 1,463,655	$ 55,057	$ 862,153	$ 860,138	$ (15,678)	$ (298,015)