Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Capital Surplus	Accum. Other Comprehensive Income	Retained Earnings	Treasury Stock
Balance at Dec. 31, 2010	$ 1,011,133	$ 570	$ 500,888	$ 26,965	$ 932,629	$ (449,919)
Balance (in shares) at Dec. 31, 2010		48,097,672
Increase (decrease) in shareholders' equity
Net Income	120,814				120,814
Other Comprehensive Income	19,789			19,789
Share-Based Compensation	2,001		2,001
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits	10,477	1	366		(3,193)	13,303
Common Stock Issued under Purchase and Equity Compensation Plans and Related Tax Benefits (in shares)		309,108
Common Stock Repurchased	(82,391)					(82,391)
Common Stock Repurchased (in shares)		(1,836,367)
Cash Dividends Paid ($1.35 per share)	(64,048)				(64,048)
Balance at Sep. 30, 2011	1,017,775	571	503,255	46,754	986,202	(519,007)
Balance (in shares) at Sep. 30, 2011		46,570,413
Balance at Dec. 31, 2011	1,002,667	571	507,558	35,263	1,003,938	(544,663)
Balance (in shares) at Dec. 31, 2011	45,947,116	45,947,116
Increase (decrease) in shareholders' equity
Net Income	125,789				125,789
Other Comprehensive Income	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		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)
Balance at Sep. 30, 2012	$ 1,024,562	$ 571	$ 513,758	$ 42,424	$ 1,065,245	$ (597,436)
Balance (in shares) at Sep. 30, 2012	45,004,813	45,004,813