Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2009	$ 78	$ 590,864	$ 11,322	$ 509,392	$ (999,121)	$ 112,535
Net income				96,285		96,285
Other comprehensive income (loss)			3,316			3,316
Issuances under stock plans		(30,254)			53,822	23,568
Stock compensation tax benefits		18,520				18,520
Common share repurchases					(99,820)	(99,820)
Stock compensation expense		32,652				32,652
Balance at Dec. 31, 2010	78	611,782	14,638	605,677	(1,045,119)	187,056
Net income				136,902		136,902
Other comprehensive income (loss)			(8,845)			(8,845)
Issuances under stock plans		(23,579)			43,624	20,045
Stock compensation tax benefits		25,778				25,778
Common share repurchases					(211,986)	(211,986)
Stock compensation expense		32,834				32,652
Balance at Dec. 31, 2011	78	646,815	5,793	742,579	(1,213,481)	181,784
Net income				165,903		165,903
Other comprehensive income (loss)			175			175
Issuances under stock plans		(24,626)			37,059	12,433
Stock compensation tax benefits		21,304				21,304
Common share repurchases					(111,304)	(111,304)
Stock compensation expense		36,378				36,378
Balance at Dec. 31, 2012	$ 78	$ 679,871	$ 5,968	$ 908,482	$ (1,287,726)	$ 306,673