Consolidated Statements of Shareholders' Equity (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Capital Surplus	Accum. Other Compre- hensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning Balance at Dec. 31, 2011	$ 1,002,667	$ 571	$ 507,558	$ 35,263	$ 1,003,938	$ (544,663)
Beginning Balance (in shares) at Dec. 31, 2011		45,947,116
Increase (decrease) in shareholders' equity
Net Income	125,789				125,789
Other Comprehensive Income (Loss)	7,161			7,161
Share-Based Compensation	5,687		5,687
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits	10,962	0	513		(3,023)	13,472
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits (in shares)		471,104
Common Stock Repurchased	(66,245)					(66,245)
Common Stock Repurchased (in shares)		(1,413,407)
Cash Dividends Paid ($1.35 per share)	(61,459)				(61,459)
Ending Balance at Sep. 30, 2012	1,024,562	571	513,758	42,424	1,065,245	(597,436)
Ending Balance (in shares) at Sep. 30, 2012		45,004,813
Beginning Balance at Dec. 31, 2012	1,021,665	571	515,619	29,208	1,084,477	(608,210)
Beginning Balance (in shares) at Dec. 31, 2012	44,754,835	44,754,835
Increase (decrease) in shareholders' equity
Net Income	111,447				111,447
Other Comprehensive Income (Loss)	(62,718)			(62,718)
Share-Based Compensation	4,226		4,226
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits	11,729	1	665		(2,458)	13,521
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits (in shares)		444,951
Common Stock Repurchased	(33,193)					(33,193)
Common Stock Repurchased (in shares)		(660,539)
Cash Dividends Paid ($1.35 per share)	(60,470)				(60,470)
Ending Balance at Sep. 30, 2013	$ 992,686	$ 572	$ 520,510	$ (33,510)	$ 1,132,996	$ (627,882)
Ending Balance (in shares) at Sep. 30, 2013	44,539,247	44,539,247