Warrants	12 Months Ended
Dec. 31, 2017
Equity [Abstract]
Warrants	17. Warrants In May 2016, the Company sold in a registered offering an aggregate of 9,708,737 shares of common stock together with A Warrants exercisable for up to an aggregate of 7,281,553 shares of common stock and B Warrants exercisable for up to an aggregate of 2,427,184 shares of common stock with a total fair value of $44.7 million. Each of the warrants had an exercise price of $7.50 per share. The A Warrants became exercisable upon issuance and expired two years thereafter. The B Warrants became exercisable beginning in May 2017 and expired 30 months after the date of issuance. The shares of common stock and the warrants are immediately separable and issued separately. The Company determined that the A Warrants required liability classification primarily due to a price-protection clause that applies in the event of certain dilutive financings. The fair value of the A Warrants was recorded as a warrant liability in the consolidated balance sheet at issuance and was adjusted to fair value at each reporting period until exercise or expiration. The Company determined that the B Warrants met the criteria for equity classification and accounted for such warrants in additional paid in capital. On September 29, 2017 the Company and four holders of 9.7 million A and B Warrants entered into separate, privately-negotiated exchange agreements, pursuant to which the Company agreed to issue to such holders an aggregate of 1,292,510 shares of the Company’s common stock (to be delivered on October 3, 2017) in exchange for such warrants. The warrant liability associated with the exchanged warrants was adjusted to fair value and $1.9 million, the fair value of the remaining obligation was reclassified into equity as of September 29, 2017. In addition, as of December 31, 2017, warrants to acquire approximately 32,000 shares of common stock were outstanding. See Note 11 – Common and Preferred Stock, for additional information.

17. Warrants

In May 2016, the Company sold in a registered offering an aggregate of 9,708,737 shares of common stock together with A Warrants exercisable for up to an aggregate of 7,281,553 shares of common stock and B Warrants exercisable for up to an aggregate of 2,427,184 shares of common stock with a total fair value of $44.7 million. Each of the warrants had an exercise price of $7.50 per share. The A Warrants became exercisable upon issuance and expired two years thereafter. The B Warrants became exercisable beginning in May 2017 and expired 30 months after the date of issuance. The shares of common stock and the warrants are immediately separable and issued separately.

The Company determined that the A Warrants required liability classification primarily due to a price-protection clause that applies in the event of certain dilutive financings. The fair value of the A Warrants was recorded as a warrant liability in the consolidated balance sheet at issuance and was adjusted to fair value at each reporting period until exercise or expiration. The Company determined that the B Warrants met the criteria for equity classification and accounted for such warrants in additional paid in capital.

On September 29, 2017 the Company and four holders of 9.7 million A and B Warrants entered into separate, privately-negotiated exchange agreements, pursuant to which the Company agreed to issue to such holders an aggregate of 1,292,510 shares of the Company’s common stock (to be delivered on October 3, 2017) in exchange for such warrants. The warrant liability associated with the exchanged warrants was adjusted to fair value and $1.9 million, the fair value of the remaining obligation was reclassified into equity as of September 29, 2017.

In addition, as of December 31, 2017, warrants to acquire approximately 32,000 shares of common stock were outstanding. See Note 11 – Common and Preferred Stock, for additional information.