Convertible Preferred Stock Warrants	12 Months Ended
Dec. 31, 2013
Convertible Preferred Stock Warrants
Convertible Preferred Stock Warrants	10. Convertible Preferred Stock Warrants In June 2013, in conjunction with the execution of the loan and security agreement (Note 9), the Company issued to the lender a warrant to purchase up to 49,602 shares of Series C convertible preferred stock with an exercise price of $7.56 per share. Upon the draw down of the $5.0 million term loan, the warrant became exercisable for 24,801 shares. If the Company draws the second term loan, the remaining 24,801 shares will become exercisable under the warrant. The warrant expires at the earlier of (i) June 26, 2023 or (ii) the seventh anniversary of the Company's initial public offering. The warrant is exercisable in cash or through a cashless exercise provision. In connection with the IPO, as more fully described in Note 11, all of the Company's outstanding shares of convertible preferred stock were automatically converted into common stock and as a result, the warrant became exercisable for 24,801 shares of common stock (or 49,602 shares in the aggregate if the Company draws down the second term loan), at an exercise price of $7.56 per share. The fair value of the then currently exercisable portion of the warrant in the amount of $175,000 was recorded as a preferred stock warrant liability upon issuance and is subject to remeasurement at each reporting period up to the closing date of the IPO when the Series C preferred stock converted into common stock. The fair value of the warrant upon issuance was calculated using the Black-Scholes option-pricing valuation model with the following assumptions: Series C preferred stock value of $2.40 per share, contractual term of 7.3 years, risk-free interest rate of 2.1%, expected volatility of 73.7%, and expected dividend yield of 0%. Just prior to the closing of the IPO, the fair value of the warrant was approximately $261,000, and was calculated using the Black-Scholes option-pricing valuation model with the following assumptions: Series C preferred stock value of $13.14 per share, contractual term of 7.0 years, risk-free interest rate of 2.0%, expected volatility of 81.4%, and expected dividend yield of 0%. The change in the fair value of approximately $86,000 was reported as an expense for the year ended December 31, 2013 and is included in other income (expense), net in the statements of operations. The warrant was converted into a warrant to purchase common stock upon the completion of the IPO in 2013, and was reclassified to additional paid-in-capital in the Company's balance sheet. As a result, the warrant is no longer subject to fair value remeasurement. The warrant was exercised through a cashless exercise on March 17, 2014 resulting in the issuance of a net 13,739 shares of the Company's common stock.

10. Convertible Preferred Stock Warrants

In June 2013, in conjunction with the execution of the loan and security agreement (Note 9), the Company issued to the lender a warrant to purchase up to 49,602 shares of Series C convertible preferred stock with an exercise price of $7.56 per share. Upon the draw down of the $5.0 million term loan, the warrant became exercisable for 24,801 shares. If the Company draws the second term loan, the remaining 24,801 shares will become exercisable under the warrant. The warrant expires at the earlier of (i) June 26, 2023 or (ii) the seventh anniversary of the Company's initial public offering. The warrant is exercisable in cash or through a cashless exercise provision. In connection with the IPO, as more fully described in Note 11, all of the Company's outstanding shares of convertible preferred stock were automatically converted into common stock and as a result, the warrant became exercisable for 24,801 shares of common stock (or 49,602 shares in the aggregate if the Company draws down the second term loan), at an exercise price of $7.56 per share.

The fair value of the then currently exercisable portion of the warrant in the amount of $175,000 was recorded as a preferred stock warrant liability upon issuance and is subject to remeasurement at each reporting period up to the closing date of the IPO when the Series C preferred stock converted into common stock. The fair value of the warrant upon issuance was calculated using the Black-Scholes option-pricing valuation model with the following assumptions: Series C preferred stock value of $2.40 per share, contractual term of 7.3 years, risk-free interest rate of 2.1%, expected volatility of 73.7%, and expected dividend yield of 0%. Just prior to the closing of the IPO, the fair value of the warrant was approximately $261,000, and was calculated using the Black-Scholes option-pricing valuation model with the following assumptions: Series C preferred stock value of $13.14 per share, contractual term of 7.0 years, risk-free interest rate of 2.0%, expected volatility of 81.4%, and expected dividend yield of 0%. The change in the fair value of approximately $86,000 was reported as an expense for the year ended December 31, 2013 and is included in other income (expense), net in the statements of operations. The warrant was converted into a warrant to purchase common stock upon the completion of the IPO in 2013, and was reclassified to additional paid-in-capital in the Company's balance sheet. As a result, the warrant is no longer subject to fair value remeasurement.

The warrant was exercised through a cashless exercise on March 17, 2014 resulting in the issuance of a net 13,739 shares of the Company's common stock.