Warrant Liability	6 Months Ended
Jun. 30, 2012
Warrant liability [Abstract]
Warrant liability	9. Warrant liability In connection with the sale of units in February 2012, the Company issued separable warrants representing 21,562,500 shares of common stock which are exercisable at $2.40 per share and are exercisable any time prior to February 8, 2016. Warrants representing 60 shares of common stock have been exercised as of June 30, 2012. Of the 21,562,500 shares represented by warrants, 16,145,833 shares were recorded as equity as they met the criteria for equity classification under ASC 815-40 Derivatives and Hedging, Contracts in an Entity’s Own Stock. The remaining warrants representing 5,416,667 shares require liability classification in accordance with ASC 480, Distinguishing Liabilities from Equity, as the Company did not have sufficient registered shares available at the time of issuance. The fair value of these shares was recorded in accrued expenses and other current liabilities in the condensed consolidated balance sheet. The warrants will be reported as a liability until they are exercised, or at the time that the Company has sufficient registered shares available, at which time the warrants will be adjusted to fair value and reclassified from liabilities to stockholders’ equity. The warrants requiring liability classification were recorded at fair value at issuance and will be adjusted to fair value at each reporting period until exercised or expiration. The fair value of the warrant liability at the date of issuance was $7.6 million and was estimated using the Black-Scholes option pricing model, based on the following assumptions: expected dividend yield of 0%; expected volatility of 93%; risk free interest rate of 0.59%; and contractual term of 4.0 years. As of March 31, 2012, the fair value of the warrant liability was $7.9 million and was estimated using the Black-Scholes option pricing model based on the following assumptions: expected dividend yield of 0%; expected volatility of 93%; risk-free interest rate of 0.59%; and contractual term of 4 years. Any change in fair value between reporting periods is recorded as other income (expense) in the condensed consolidated statements of operations. During the quarter ended March 31, 2012, a loss of $284,000 was recognized from the fair value adjustment of the warrant liability. As of June 30, 2012, the fair value of the warrant liability was $4.9 million and was estimated using the Black-Scholes option pricing model based on the following assumptions: expected dividend yield of 0%; expected volatility of 75.7%; risk-free interest rate of 0.41%; and contractual term of 3.6 years. Any change in fair value between reporting periods is recorded as other income (expense) in the condensed consolidated statements of operations. During the quarter ended June 30, 2012, a gain of $3.0 million was recognized from the fair value adjustment of the warrant liability. The fair value of the warrant liability is highly sensitive to the volatility rate used in the option pricing model and an increase in the volatility rate would cause an increase in the warrant liability. The volatility assumption is calculated based on historical activity.

Warrant Liability

6 Months Ended

Jun. 30, 2012

9. Warrant liability

In connection with the sale of units in February 2012, the Company issued separable warrants representing 21,562,500 shares of common stock which are exercisable at $2.40 per share and are exercisable any time prior to February 8, 2016. Warrants representing 60 shares of common stock have been exercised as of June 30, 2012.

Of the 21,562,500 shares represented by warrants, 16,145,833 shares were recorded as equity as they met the criteria for equity classification under ASC 815-40 Derivatives and Hedging, Contracts in an Entity’s Own Stock. The remaining warrants representing 5,416,667 shares require liability classification in accordance with ASC 480, Distinguishing Liabilities from Equity, as the Company did not have sufficient registered shares available at the time of issuance. The fair value of these shares was recorded in accrued expenses and other current liabilities in the condensed consolidated balance sheet. The warrants will be reported as a liability until they are exercised, or at the time that the Company has sufficient registered shares available, at which time the warrants will be adjusted to fair value and reclassified from liabilities to stockholders’ equity.

The warrants requiring liability classification were recorded at fair value at issuance and will be adjusted to fair value at each reporting period until exercised or expiration. The fair value of the warrant liability at the date of issuance was $7.6 million and was estimated using the Black-Scholes option pricing model, based on the following assumptions: expected dividend yield of 0%; expected volatility of 93%; risk free interest rate of 0.59%; and contractual term of 4.0 years.

As of March 31, 2012, the fair value of the warrant liability was $7.9 million and was estimated using the Black-Scholes option pricing model based on the following assumptions: expected dividend yield of 0%; expected volatility of 93%; risk-free interest rate of 0.59%; and contractual term of 4 years. Any change in fair value between reporting periods is recorded as other income (expense) in the condensed consolidated statements of operations. During the quarter ended March 31, 2012, a loss of $284,000 was recognized from the fair value adjustment of the warrant liability.

As of June 30, 2012, the fair value of the warrant liability was $4.9 million and was estimated using the Black-Scholes option pricing model based on the following assumptions: expected dividend yield of 0%; expected volatility of 75.7%; risk-free interest rate of 0.41%; and contractual term of 3.6 years. Any change in fair value between reporting periods is recorded as other income (expense) in the condensed consolidated statements of operations. During the quarter ended June 30, 2012, a gain of $3.0 million was recognized from the fair value adjustment of the warrant liability. The fair value of the warrant liability is highly sensitive to the volatility rate used in the option pricing model and an increase in the volatility rate would cause an increase in the warrant liability. The volatility assumption is calculated based on historical activity.