Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Subscription Receivable [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Items [Member]	Total
Balance, Shares at Dec. 31, 2012	25,593			104
Balance, Amount at Dec. 31, 2012	$ 25	$ (129)	$ 253,210		$ (192,722)	$ 17	$ 60,401
Stock based compensation resulting from stock options granted to employees and board of directors			24,204				24,204
Stock based compensation resulting from stock options granted to nonemployees			3,716				3,716
Issuance of common stock, Shares	3,111
Issuance of common stock, Amount	$ 3		78,017				78,020
Stock options exercised, Shares	784
Stock options exercised, Amount	$ 1	$ 129	9,908				10,038
Net loss					(63,358)		(63,358)
Unrealized gain (loss) on marketable securities						34	34
Foreign currency translation						(23)	(23)
Balance, Shares at Dec. 31, 2013	29,488			104
Balance, Amount at Dec. 31, 2013	$ 29		369,055		(256,080)	28	113,032
Stock based compensation resulting from stock options granted to employees and board of directors			30,377				30,377
Reversal of tax benefit from stock-based compensation			62				62
Issuance of warrants			60,547				60,547
Purchase of convertible bond hedges			(86,645)				(86,645)
Equity component of convertible debt			116,900				116,900
Equity component of deferred financing costs for convertible debt			(3,039)				(3,039)
Stock options exercised, Shares	228
Stock options exercised, Amount	$ 1		3,737				3,738
Repurchase of common stock, Shares				1,147
Repurchase of common stock, Amount				$ (35,000)			(35,000)
Net loss					(39,385)		(39,385)
Unrealized gain (loss) on marketable securities						(35)	(35)
Foreign currency translation						(256)	(256)
Balance, Shares at Dec. 31, 2014	29,716			1,251
Balance, Amount at Dec. 31, 2014	$ 30		490,994	$ (35,000)	(295,465)	(263)	160,296
Stock based compensation resulting from stock options granted to employees and board of directors			24,348				24,348
Reversal of tax benefit from stock-based compensation			(62)				$ (62)
Stock options exercised, Shares	961						961
Stock options exercised, Amount	$ 1		4,254				$ 4,255
Vesting of restricted stock, net of shares withheld for taxes			(368)				(368)
Vesting of restricted stock, net of shares withheld for taxes, shares	38
Net loss					(73,339)		(73,339)
Foreign currency translation						415	415
Balance, Shares at Dec. 31, 2015	30,715			1,251
Balance, Amount at Dec. 31, 2015	$ 31		$ 519,166	$ (35,000)	$ (368,804)	$ 152	$ 115,545