STATEMENT OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total USD ($)	Options USD ($)	April 2010 Warrants USD ($)	June 2010 USD ($)	July 2011 USD ($)	July 2011 Warrants USD ($)	March 2012 Warrants USD ($)	Committed Equity Financing Facility with Kingsbridge Capital Limited USD ($)	Public financing transaction July 2011 USD ($)	Public financing transaction March 2012 USD ($)	Private equity transaction March 2012 Warrants USD ($)	Employees and Directors USD ($)	Employees and Directors Options USD ($)	Consultants USD ($)	Consultants Options USD ($)	Common Stock USD ($)	Common Stock Options USD ($)	Common Stock April 2010 Warrants USD ($)	Common Stock June 2010 USD ($)	Common Stock July 2011	Common Stock Committed Equity Financing Facility with Kingsbridge Capital Limited USD ($)	Common Stock Public financing transaction July 2011 USD ($)	Common Stock Public financing transaction March 2012 USD ($)	Common Stock Private equity transaction March 2012 Warrants USD ($)	Additional Paid-in Capital USD ($)	Additional Paid-in Capital Options USD ($)	Additional Paid-in Capital April 2010 Warrants USD ($)	Additional Paid-in Capital June 2010 USD ($)	Additional Paid-in Capital July 2011 USD ($)	Additional Paid-in Capital July 2011 Warrants USD ($)	Additional Paid-in Capital March 2012 Warrants USD ($)	Additional Paid-in Capital Committed Equity Financing Facility with Kingsbridge Capital Limited USD ($)	Additional Paid-in Capital Public financing transaction July 2011 USD ($)	Additional Paid-in Capital Public financing transaction March 2012 USD ($)	Additional Paid-in Capital Private equity transaction March 2012 Warrants USD ($)	Additional Paid-in Capital Employees and Directors USD ($)	Additional Paid-in Capital Employees and Directors Options USD ($)	Additional Paid-in Capital Consultants USD ($)	Additional Paid-in Capital Consultants Options USD ($)	Notes Receivable from Stockholders USD ($)	Accumulated Deficit USD ($)
Beginning Balance at Dec. 31, 2009	$ 22,092															$ 62									$ 172,369															$ (101)	$ (150,238)
Beginning Balance (in shares) at Dec. 31, 2009																62,475,000
Issuance of stock (in shares)																		4,286,000	5,000,000		519,000
Issuance of stock			7,484	13,753				1,610										4	5		1						7,480	13,748				1,609
Repayment of notes receivable from stockholders	4																																							4
Stock-based compensation												1,947		169																						1,947		169
Net loss and comprehensive loss	(25,966)																																								(25,966)
Issuance of common stock upon options exercise for cash (in shares)	124,000															124,000
Issuance of common stock upon options exercise for cash	151																								151
Ending Balance at Dec. 31, 2010	21,244															72									197,473															(97)	(176,204)
Ending Balance (in shares) at Dec. 31, 2010																72,404,000
Issuance of stock (in shares)																						11,500,000
Issuance of stock									41,783													12											41,771
Repayment of notes receivable from stockholders	97																																							97
Issuance of common stock upon exercise of warrants (in shares)																				81,000
Issuance of common stock upon exercise of warrants						231																								231
Stock-based compensation													3,016		419																						3,016		419
Net loss and comprehensive loss	(32,354)																																								(32,354)
Issuance of common stock upon options exercise for cash (in shares)	246,000																			246,000
Issuance of common stock upon options exercise for cash					371																								371
Ending Balance at Dec. 31, 2011	34,807															84									243,281																(208,558)
Ending Balance (in shares) at Dec. 31, 2011																84,231,000
Issuance of stock (in shares)																							11,000,000	4,202,000
Issuance of stock										46,130	12,819												11	4										46,119	12,815
Issuance of common stock upon exercise of warrants (in shares)																								216,000
Issuance of common stock upon exercise of warrants							470																								470
Stock-based compensation													5,102		208																						5,102		208
Net loss and comprehensive loss	(38,048)																																								(38,048)
Issuance of common stock upon options exercise for cash (in shares)	165,000																165,000
Issuance of common stock upon options exercise for cash		289															1									288
Ending Balance at Dec. 31, 2012	$ 61,777															$ 100									$ 308,283																$ (246,606)
Ending Balance (in shares) at Dec. 31, 2012																99,814,000