Stockholders' Equity	12 Months Ended
Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	9. Stockholders’ Equity The Company’s Board of Directors has authorized 100,000,000 shares of the Company’s common stock, par value $0.001 per share, and 5,000,000 shares of undesignated preferred stock, par value $0.001 per share, that may be issued from time to time by the Board of Directors of the Company in one or more series. As of December 31, 2017, there were 32,662,255 shares of common stock and no shares of preferred stock issued and outstanding. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to dividends when and if declared by the Board of Directors, subject to the preferential rights of the holders of preferred stock, if any. On July 29, 2015, the Company entered into an underwriting agreement, or the Underwriting Agreement, with Stifel, Nicolaus & Company, Incorporated and Piper Jaffray & Co., as representatives of the several underwriters named therein, relating to the issuance and sale by the Company of 3,763,440 shares of its common stock, or the 2015 Offering. The 2015 Offering was made pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-203072), filed with the SEC on March 27, 2015 and declared effective on May 13, 2015, and a related prospectus supplement dated July 29, 2015, which was filed with the SEC on July 30, 2015. As part of the 2015 Offering, the Company granted the underwriters an option to purchase 564,516 additional shares of common stock. On August 4, 2015, the Company closed the 2015 Offering, including the full exercise of the underwriters’ option to purchase 564,516 additional shares of common stock, at a public offering price of $18.60 per share. The Company received net proceeds of approximately $75,231, after deducting the underwriting discounts and commissions and offering expenses paid by the Company of $5,269. On March 30, 2017, the Company entered into an underwriting agreement with Piper Jaffray & Co. and Stifel, Nicolaus & Company, Incorporated, as representatives of the several underwriters named therein, relating to the issuance and sale by the Company of 5,117,500 shares of its common stock, including 667,500 shares of common stock the underwriters had the option to purchase, at a public offering price of $18.00 per share, or the 2017 Offering. The 2017 Offering was made pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-216657), filed with the SEC on March 13, 2017 and declared effective on March 24, 2017, and a related prospectus supplement dated March 30, 2017, which was filed with the SEC on March 31, 2017. On April 5, 2017, the Company closed the 2017 Offering, including the full exercise of the underwriters’ option to purchase 667,500 additional shares of common stock. The Company received net proceeds of approximately $86,224, after deducting the underwriting discounts and commissions and offering expenses paid by the Company of $5,891.

9. Stockholders’ Equity

The Company’s Board of Directors has authorized 100,000,000 shares of the Company’s common stock, par value $0.001 per share, and 5,000,000 shares of undesignated preferred stock, par value $0.001 per share, that may be issued from time to time by the Board of Directors of the Company in one or more series. As of December 31, 2017, there were 32,662,255 shares of common stock and no shares of preferred stock issued and outstanding.

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to dividends when and if declared by the Board of Directors, subject to the preferential rights of the holders of preferred stock, if any.

On July 29, 2015, the Company entered into an underwriting agreement, or the Underwriting Agreement, with Stifel, Nicolaus & Company, Incorporated and Piper Jaffray & Co., as representatives of the several underwriters named therein, relating to the issuance and sale by the Company of 3,763,440 shares of its common stock, or the 2015 Offering. The 2015 Offering was made pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-203072), filed with the SEC on March 27, 2015 and declared effective on May 13, 2015, and a related prospectus supplement dated July 29, 2015, which was filed with the SEC on July 30, 2015. As part of the 2015 Offering, the Company granted the underwriters an option to purchase 564,516 additional shares of common stock.

On August 4, 2015, the Company closed the 2015 Offering, including the full exercise of the underwriters’ option to purchase 564,516 additional shares of common stock, at a public offering price of $18.60 per share. The Company received net proceeds of approximately $75,231, after deducting the underwriting discounts and commissions and offering expenses paid by the Company of $5,269.

On March 30, 2017, the Company entered into an underwriting agreement with Piper Jaffray & Co. and Stifel, Nicolaus & Company, Incorporated, as representatives of the several underwriters named therein, relating to the issuance and sale by the Company of 5,117,500 shares of its common stock, including 667,500 shares of common stock the underwriters had the option to purchase, at a public offering price of $18.00 per share, or the 2017 Offering. The 2017 Offering was made pursuant to the Company’s Registration Statement on Form S-3 (File No. 333-216657), filed with the SEC on March 13, 2017 and declared effective on March 24, 2017, and a related prospectus supplement dated March 30, 2017, which was filed with the SEC on March 31, 2017.

On April 5, 2017, the Company closed the 2017 Offering, including the full exercise of the underwriters’ option to purchase 667,500 additional shares of common stock. The Company received net proceeds of approximately $86,224, after deducting the underwriting discounts and commissions and offering expenses paid by the Company of $5,891.