Shelf Registration Statement	12 Months Ended
Dec. 31, 2017
Stock Offering [Abstract]
Shelf Registration Statement	Shelf Registration Statements On November 9, 2017, the Company filed a shelf registration statement on Form S-3 with the SEC to, from time to time, sell up to an aggregate of $125 million of any combination of its common stock, warrants, debt securities or units. On November 16, 2017, the registration statement was declared effective by the SEC, which will allow the Company to access the capital markets for the three-year period following this effective date. As of December 31, 2017, no securities have been issued under the Company’s shelf registration statement. Net proceeds, terms and pricing of each offering of securities issued under the shelf registration statement will be determined at the time of such offerings. On April 23, 2015, under a previous shelf registration statement effective June 30, 2014, the Company entered into an At-the-Market Equity Offering Sales Agreement (“Sales Agreement”) with Cowen and Company, LLC (“Cowen”) pursuant to which they could sell, up to an aggregate of $10.0 million in shares of common stock through Cowen, as sales agent. Under the Sales Agreement, the Company agreed to pay Cowen a commission equal to 3.0% of the gross proceeds from the sale of shares of our common stock. On June 11, 2015, the Company completed the sale of approximately $10.0 million of common stock and terminated the offering. Approximately 1.83 million shares were sold in the offering at an average share price of $5.46. The Company received net proceeds of $9.6 million after commissions and offering costs of $0.4 million.

Shelf Registration Statements

On November 9, 2017, the Company filed a shelf registration statement on Form S-3 with the SEC to, from time to time, sell up to an aggregate of $125 million of any combination of its common stock, warrants, debt securities or units. On November 16, 2017, the registration statement was declared effective by the SEC, which will allow the Company to access the capital markets for the three-year period following this effective date. As of December 31, 2017, no securities have been issued under the Company’s shelf registration statement. Net proceeds, terms and pricing of each offering of securities issued under the shelf registration statement will be determined at the time of such offerings.

On April 23, 2015, under a previous shelf registration statement effective June 30, 2014, the Company entered into an At-the-Market Equity Offering Sales Agreement (“Sales Agreement”) with Cowen and Company, LLC (“Cowen”) pursuant to which they could sell, up to an aggregate of $10.0 million in shares of common stock through Cowen, as sales agent. Under the Sales Agreement, the Company agreed to pay Cowen a commission equal to 3.0% of the gross proceeds from the sale of shares of our common stock. On June 11, 2015, the Company completed the sale of approximately $10.0 million of common stock and terminated the offering. Approximately 1.83 million shares were sold in the offering at an average share price of $5.46. The Company received net proceeds of $9.6 million after commissions and offering costs of $0.4 million.