Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Noncontrolling Interest in JV [Member]
Balance at Dec. 31, 2011	$ 511,642	$ 54	$ 0	$ 623,801	$ (111,665)	$ (548)	$ 0
Balance, shares at Dec. 31, 2011		54,312,000	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock purchases	22,932	2		22,930
Employee stock purchase, shares	1,487,642	1,488,000
Issuance of restricted stock awards	0	0
Issuance of restricted stock awards, shares	352,391	352,000
Non-cash stock compensation	14,981			14,981
Excess tax benefit from share-based compensation arrangements	1,558			1,558
Equity component of the convertible notes, issuance, net	55,685			55,685
Purchase of convertible note hedges	(58,223)			(58,223)
Sale of warrants	38,425			38,425
Purchase of treasury stock	(50,000)		(50,000)
Purchase of treasury stock, shares			(2,193,000)
Debt issuance costs	(1,730)			(1,730)
(Loss) net income	51,170				51,254		(84)
Currency translation adjustment	(224)					(224)
Unrealized (loss) gain on available for sale securities	6					6
Balance at Dec. 31, 2012	586,222	56	(50,000)	697,427	(60,411)	(766)	(84)
Balance, shares at Dec. 31, 2012		56,152,000	(2,193,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock purchases	74,213	4		74,209
Employee stock purchase, shares	3,547,431	3,547,000
Issuance of restricted stock awards	0	0
Issuance of restricted stock awards, shares	237,413	237,000
Issuance of common stock	189,599	6		189,593
Issuance of common stock, shares		6,653,000
Non-cash stock compensation	23,078			23,078
Excess tax benefit from share-based compensation arrangements	7,675			7,675
(Loss) net income	15,260				15,512		(252)
Currency translation adjustment	(3,876)					(3,876)
Unrealized (loss) gain on available for sale securities	(10)					(10)
Balance at Dec. 31, 2013	892,161	66	(50,000)	991,982	(44,899)	(4,652)	(336)
Balance, shares at Dec. 31, 2013		66,589,000	(2,193,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock purchases	17,343	1		17,342
Employee stock purchase, shares	864,457	864,000
Issuance of restricted stock awards	1	1
Issuance of restricted stock awards, shares	212,136	214,000
Non-cash stock compensation	34,311			34,311
Excess tax benefit from share-based compensation arrangements	1,443			1,443
(Loss) net income	(32,348)				(32,210)		(138)
Currency translation adjustment	7,180					7,180
Unrealized (loss) gain on available for sale securities
Balance at Dec. 31, 2014	$ 920,091	$ 68	$ (50,000)	$ 1,045,078	$ (77,109)	$ 2,528	$ (474)
Balance, shares at Dec. 31, 2014		67,667,000	(2,193,000)