Consolidated Statement Of Changes In Stockholders' Equity (USD $)	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Beginning Balance at Dec. 31, 2012	$ 2,640,657,000	$ 1,841,000	$ 863,558,000	$ 2,548,542,000	$ 21,767,000	$ (795,051,000)
Beginning Balance (in shares) at Dec. 31, 2012	184,059,900	184,060,000
Net income	96,998,000			96,998,000
Foreign currency translation adjustment	(6,051,000)				(6,051,000)
Issuance of restricted stock (in shares)		1,220,000
Issuance of restricted stock		12,000	(12,000)
Vesting of stock unit awards		8,000
Forfeitures of restricted stock (in shares)		(32,000)
Forfeitures of restricted stock
Exercise of stock options (in shares)	1,190,000	1,190,000
Exercise of stock options	19,286,000	11,000	19,275,000
Stock-based compensation	12,119,000		12,119,000
Tax benefit related to stock-based compensation	4,862,000		4,862,000
Payment of cash dividends	(14,673,000)			(14,673,000)
Purchase of treasury stock	(22,358,000)					(22,358,000)
Ending Balance at Jun. 30, 2013	$ 2,730,840,000	$ 1,864,000	$ 899,802,000	$ 2,630,867,000	$ 15,716,000	$ (817,409,000)
Ending Balance (in shares) at Jun. 30, 2013	186,446,351	186,446,000