Preferred Stock Warrant Liabilities	12 Months Ended
Dec. 31, 2012
Preferred Stock Warrant Liabilities	8. Preferred Stock Warrant Liabilities In connection with a credit facility obtained in 2005, the Company issued a warrant to purchase 15,599 shares of Series B-2 convertible preferred stock (Series B-2 Preferred) upon the signing of the credit facility agreement in October 2005, which was increased to 38,997 shares of Series B-2 Preferred upon draw down of the loan in December 2006. The warrant was immediately exercisable upon issuance and expires on October 31, 2015. The exercise price per share is $5.13. The warrant converted into a warrant exercisable into the Company’s common stock upon the completion of the Company’s IPO with the same exercise price per share of $5.13. In connection with the Agreement with MidCap Financial, in September 2012 and December 2012 the Company issued warrants to purchase shares of Series E Preferred in an amount equal to 4% of the amount drawn down under the Agreement divided by the Series E Preferred exercise price of $12.11 per share. The warrants were immediately exercisable for 33,032 shares of Series E Preferred upon issuance. The Series E Preferred warrant expired upon the completion of the Company’s IPO in February 2013.

8. Preferred Stock Warrant Liabilities

In connection with a credit facility obtained in 2005, the Company issued a warrant to purchase 15,599 shares of Series B-2 convertible preferred stock (Series B-2 Preferred) upon the signing of the credit facility agreement in October 2005, which was increased to 38,997 shares of Series B-2 Preferred upon draw down of the loan in December 2006. The warrant was immediately exercisable upon issuance and expires on October 31, 2015. The exercise price per share is $5.13. The warrant converted into a warrant exercisable into the Company’s common stock upon the completion of the Company’s IPO with the same exercise price per share of $5.13.

In connection with the Agreement with MidCap Financial, in September 2012 and December 2012 the Company issued warrants to purchase shares of Series E Preferred in an amount equal to 4% of the amount drawn down under the Agreement divided by the Series E Preferred exercise price of $12.11 per share. The warrants were immediately exercisable for 33,032 shares of Series E Preferred upon issuance. The Series E Preferred warrant expired upon the completion of the Company’s IPO in February 2013.