Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events On July 24, 2017, pursuant to its shelf registration statement on Form S-3, the Company completed the issuance of 14,950,000 shares of its common stock at $6.50 per share in an underwritten public offering, which the Company refers to as the July 2017 public offering. Net proceeds to the Company in connection with the July 2017 public offering were approximately $91.1 million after deducting underwriting discounts, commissions and other offering expenses. In connection with the July 2017 public offering, the Company terminated its $25 million ATM facility with JonesTrading Institutional Services LLC.