Consolidated Statements of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	(Accumulated Deficit) Retained Earnings	Accumulated Other Comprehensive Income
Balance at Dec. 31, 2009	$ 359,059	$ 382		$ 575,860	$ (224,324)	$ 7,141
Balance (in shares) at Dec. 31, 2009		39,003,114
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	45,164	25		45,139
Exercise of stock options (in shares)		2,499,591
Equity-based compensation expense-continuing operations	8,769			8,769
Equity-based compensation expense-discontinued operations	8,551			8,551
Issuance, vesting and cancellation of restricted stock	(4,619)	2		(4,621)
Issuance, vesting and cancellation of restricted stock (in shares)		(46,155)
Treasury stock	(38,098)		(38,098)
Treasury stock (in shares)	(1,118,600)	(1,118,600)	(1,118,600)
Excess tax benefits from stock option exercises	23,271			23,271
Foreign currency translation	(1,322)					(1,322)
Minimum pension liability	(120)					(120)
Unrealized (loss) gain on available-for-sale securities	99					99
Reclassification adjustments for gains included in net income	(2)					(2)
Net income	361,760				361,760
Balance at Dec. 31, 2010	762,512	409	(38,098)	656,969	137,436	5,796
Balance (in shares) at Dec. 31, 2010		40,337,950
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	10,714	7		10,707
Exercise of stock options (in shares)		688,105
Equity-based compensation expense-continuing operations	12,807			12,807
Equity-based compensation expense-discontinued operations	689			689
Issuance, vesting and cancellation of restricted stock	(3,174)	1		(3,175)
Issuance, vesting and cancellation of restricted stock (in shares)		131,196
Treasury stock	(162,077)		(162,077)
Treasury stock (in shares)	(4,160,228)	(4,160,228)	(4,160,228)
Debt conversion	(32)	18		(50)
Debt conversion (in shares)		1,771,413
Excess tax benefits from stock option exercises	10,406			10,406
Foreign currency translation	688				(106)	794
Minimum pension liability	(43)					(43)
Unrealized (loss) gain on available-for-sale securities	314					314
Reclassification adjustments for gains included in net income	(271)					(271)
Net income	127,987				127,987
Balance at Dec. 31, 2011	760,520	435	(200,175)	688,353	265,317	6,590
Balance (in shares) at Dec. 31, 2011		38,768,436
Increase (Decrease) in Stockholders' Equity
Exercise of stock options	5,409	4		5,405
Exercise of stock options (in shares)		351,436
Equity-based compensation expense-continuing operations	14,268			14,268
Issuance, vesting and cancellation of restricted stock	(1,725)	7		(1,732)
Issuance, vesting and cancellation of restricted stock (in shares)		208,631
Treasury stock		(53)	200,175		(200,122)
Debt conversion	310			310
Excess tax benefits from stock option exercises	2,119			2,119
Foreign currency translation	(388)					(388)
Minimum pension liability	(137)					(137)
Unrealized (loss) gain on available-for-sale securities	(68)					(68)
Reclassification adjustments for gains included in net income	(24)					(24)
Net income	30,928				30,928
Balance at Dec. 31, 2012	$ 811,212	$ 393		$ 708,723	$ 96,123	$ 5,973
Balance (in shares) at Dec. 31, 2012		39,328,503