Consolidated Statements of Convertible Preferred Stock, Non-Controlling Interest and Stockholders' Deficit (USD $) In Thousands, except Share data	Total	Temporary Equity, Parent [Member] Series B-G Convertible Preferred Stock [Member]	Temporary Equity, Parent [Member] Series G Preferred Stock [Member]	Temporary Equity, Parent [Member] Series C Preferred Stock [Member]	Non-controlling Interest [Member]	Non-controlling Interest [Member] Series B-G Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2010	$ (219,964)	$ 191,257			$ 1,027		$ 111	$ 51,541		$ (271,616)
Balance (in shares) at Dec. 31, 2010		53,148,000
Balance (in shares) at Dec. 31, 2010							11,073,000
Loss attributable to non-controlling interest	453				(453)					453
Issuance of Series C stock as a result of warrant exercises				19
Exercise of stock options and common stock warrants	1,745						7	1,738
Issuance of Series C stock as a result of warrant exercises (in shares)				3,000
Issuance of Series G stock			76,949
Exercise of stock options and common stock warrants (shares)							761,000
Issuance of Series G stock (in shares)			11,000,000
Stock-based compensation	6,952							6,952
Net loss	(79,676)									(79,676)
Balance at Dec. 31, 2011	(290,490)	268,225			574		118	60,231		(350,839)
Balance (in shares) at Dec. 31, 2011							11,834,000
Balance (in shares) at Dec. 31, 2011		64,151,000
Loss attributable to non-controlling interest	477				(477)					477
Exercise of stock options and common stock warrants	5,427						27	5,400
Exercise of stock options and common stock warrants (shares)							2,693,000
Stock-based compensation	6,889							6,889
Conversion of convertible preferred stock into common stock	268,225	(268,225)					663	267,562
Conversion of convertible preferred stock into common stock (in shares)		(64,151,000)					66,256,000
Initial public offering, net of issuance costs	98,081						150	97,931
Initial public offering, net of issuance costs (shares)							15,042,000
Series B dividends declared	(4,263)							(4,263)
Conversion of convertible preferred stock warrants to common stock warrants	929							929
Other comprehensive (loss) income	(38)								(38)
Net loss	(91,754)									(91,754)
Balance at Dec. 31, 2012	(6,517)				97		958	434,679	(38)	(442,116)
Balance (in shares) at Dec. 31, 2012		0
Balance (in shares) at Dec. 31, 2012							95,825,000
Issuance of common stock in a public offering, net of issuance costs (shares)
Conversion of Silver Creek convertible notes payable					796
Loss attributable to non-controlling interest	556				(556)					556
Exercise of stock options and common stock warrants	2,036						9	2,027
Exercise of stock options and common stock warrants (shares)							948,000
Stock-based compensation	10,733							10,733
Conversion of convertible preferred stock into common stock	1,807							1,807
Initial public offering, net of issuance costs	26,716						58	26,658
Initial public offering, net of issuance costs (shares)							5,750,000
Conversion option of convertible senior notes	51,875							51,875
Other comprehensive (loss) income	14								14
Net loss	(130,685)									(130,685)
Balance at Dec. 31, 2013	$ (43,465)	$ 0			$ 337		$ 1,025	$ 527,779	$ (24)	$ (572,245)
Balance (in shares) at Dec. 31, 2013							102,523,000