CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Common Stock In Treasury	Additional Paid in Capital	Retained Earnings	Warrants Outstanding	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2008	$ 908,073	$ 409	$ (136,153)	$ 589,011	$ 449,252	$ 5,382	$ 172
Balance (in shares) at Dec. 31, 2008		40,873,000	(3,867,000)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense	19,782			19,782
Exercise of stock options	2,579	1		2,578
Exercise of stock options (in shares)		77,000
Tax benefit (cost) from exercise of stock options and vesting of stock awards	2,917			2,917
Exercise of stock warrants	1			1
Issuance of equity	194			194
Issuance of equity (in shares)		94,000
Repurchase of stock	(89,667)		(89,667)
Repurchase of stock (in shares)			(2,642,000)
Net income	106,671				106,671
Other comprehensive loss-other	58
Balance at Dec. 31, 2009	950,492	410	(225,820)	614,483	555,923	5,382	114
Balance (in shares) at Dec. 31, 2009		41,044,000	(6,509,000)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense	15,102			15,102
Exercise of stock options	76,866	21		76,845
Exercise of stock options (in shares)		2,027,000
Tax benefit (cost) from exercise of stock options and vesting of stock awards	(1,384)			(1,384)
Exercise of stock warrants	16,010	6		20,966		(4,962)
Exercise of stock warrants (in shares)		526,000
Issuance of equity	(690)			(690)
Issuance of equity (in shares)		90,000
Repurchase of stock	(155,935)		(155,935)
Repurchase of stock (in shares)			(3,396,000)
Net income	138,659				138,659
Other comprehensive loss-other	105
Balance at Dec. 31, 2010	1,039,015	437	(381,755)	725,322	694,582	420	9
Balance (in shares) at Dec. 31, 2010		43,687,000	(9,905,000)
Increase (Decrease) in Stockholders' Equity
Stock compensation expense	17,256			17,256
Exercise of stock options	40,841	11		40,830
Exercise of stock options (in shares)		1,065,000
Tax benefit (cost) from exercise of stock options and vesting of stock awards	(1,213)			(1,213)
Exercise of stock warrants	955			1,251		(296)
Exercise of stock warrants (in shares)		31,000
Issuance of equity	17,980	5		17,975
Issuance of equity (in shares)		502,000
Repurchase of stock	(401,514)		(401,514)
Repurchase of stock (in shares)			(8,207,000)
Adjustment to additional paid in capital due to reversal of tax contingency	2,490			2,490
Forfeiture of stock warrants				124		(124)
Net income	129,623				129,623
Other comprehensive loss-other	159
Balance at Dec. 31, 2011	$ 845,274	$ 453	$ (783,269)	$ 804,035	$ 824,205		$ (150)
Balance (in shares) at Dec. 31, 2011		45,285,000	(18,112,000)