CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Balance at Dec. 31, 2011	$ 44	$ 271,032	$ 2,652	$ (205,006)	$ 68,722
Balance (in shares) at Dec. 31, 2011	44,210,636
Increase (Decrease) in Stockholders' Equity
Shares Issued under Stock Option and Employee Stock Purchase Plans		163			163
Shares Issued under Stock Option and Employee Stock Purchase Plans (in shares)	70,587
Shares Issued in Connection with Cantor Agreement	8	40,130			40,138
Shares Issued in Connection with Cantor Agreement (in shares)	8,003,290
Shares Issued in Underwritten Offering	12	43,471			43,483
Shares Issued in Underwritten Offering (in shares)	12,075,000				12,075,000
Share-Based Compensation		2,298			2,298
Foreign Currency Translation Adjustments Net			2		2
Unrealized Gains (Losses) on Marketable Securities			91		91
Net Loss				(59,123)	(59,123)
Balance at Dec. 31, 2012	64	357,094	2,745	(264,129)	95,774
Balance (in shares) at Dec. 31, 2012	64,359,513
Increase (Decrease) in Stockholders' Equity
Shares Issued under Stock Option and Employee Stock Purchase Plans	1	5,402			5,403
Shares Issued under Stock Option and Employee Stock Purchase Plans (in shares)	840,228
Shares Issued in Connection with Cantor Agreement	2	17,132			17,134
Shares Issued in Connection with Cantor Agreement (in shares)	2,433,608
Shares Issued in Underwritten Offering	22	278,541			278,563
Shares Issued in Underwritten Offering (in shares)	21,613,483				21,613,483
Share-Based Compensation		4,548			4,548
Foreign Currency Translation Adjustments Net			(3)		(3)
Unrealized Gains (Losses) on Marketable Securities			(74)		(74)
Net Loss				(81,550)	(81,550)
Balance at Dec. 31, 2013	89	662,717	2,668	(345,679)	319,795
Balance (in shares) at Dec. 31, 2013	89,246,832				89,246,832
Increase (Decrease) in Stockholders' Equity
Shares Issued under Stock Option and Employee Stock Purchase Plans	1	1,170			1,171
Shares Issued under Stock Option and Employee Stock Purchase Plans (in shares)	193,775
Shares Issued in Connection with Supply Agreement		2,000			2,000
Shares Issued in Connection with Supply Agreement (in shares)	152,172
Share-Based Compensation		6,852			6,852
Foreign Currency Translation Adjustments Net			(5)		(5)
Unrealized Gains (Losses) on Marketable Securities			(73)		(73)
Net Loss				(118,080)	(118,080)
Balance at Dec. 31, 2014	$ 90	$ 672,739	$ 2,590	$ (463,759)	$ 211,660
Balance (in shares) at Dec. 31, 2014	89,592,779				89,592,779