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Equity Financings and Warrants | 12 Months Ended
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Dec. 31, 2017
Equity [Abstract] |
Equity Financings and Warrants | (7) Equity Financings and Warrants 2017 Equity Financing On January 11, 2017, the Company entered into a Capital on Demand TM Sales Agreement (the Sales Agreement) with JonesTrading Institutional Services LLC, as agent (JonesTrading), pursuant to which the Company may offer and sell, from time to time through JonesTrading, shares of the Company’s common stock, par value $0.001 per share (the Common Stock), having an aggregate offering price of up to $7.3 million. On August 21, 2017, the Company amended its Capital on Demand Sales Agreement. The amendment, among other things, increased the maximum aggregate offering value of shares of the Company’s common stock which the Company may issue and sell from time to time under the Sales Agreement from $7.3 million to $10.2 million (the Shares). Under the amended Sales Agreement, JonesTrading may sell the Shares by any method permitted by law and deemed to be an “at the market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on or through The NASDAQ Capital Market, on any other existing trading market for the Common Stock or to or through a market maker. In addition, under the amended Sales Agreement, JonesTrading may sell the Shares by any other method permitted by law, including in negotiated transactions. The Company may instruct JonesTrading not to sell Shares if the sales cannot be effected at or above the price designated by the Company from time to time. The Company is not obligated to make any sales of the Shares under the amended Sales Agreement. The offering of Shares pursuant to the amended Sales Agreement will terminate upon the earlier of (a) the sale of all of the Shares subject to the amended Sales Agreement or (b) the termination of the amended Sales Agreement by JonesTrading or the Company, as permitted therein. The Company will pay JonesTrading a commission rate equal to 3.0% of the aggregate gross proceeds from each sale of Shares and have agreed to provide JonesTrading with customary indemnification and contribution rights. The Company will also reimburse JonesTrading for certain specified expenses in connection with entering into and amending the Sales Agreement. As of December 31, 2017, the Company has sold an aggregate of 2,677,525 shares of Common Stock pursuant to the terms of such Sales Agreement, as amended, for aggregate gross proceeds of approximately $6.6 million. Net proceeds received during the year ended December 31, 2017 were approximately $6.1 million, including initial expenses for executing the “at the market offering” and commissions to the placement agent. Sales under this facility subsequent to December 31, 2017 are discussed in Note 11 Subsequent Events. Warrants Warrants to purchase shares of common stock were granted as part of various financing and business agreements. All outstanding warrants were recorded in additional paid-in capital at their estimated fair market value at the date of grant using a Black-Scholes option-pricing model. As of December 31, 2017, these warrants, by year of expiration, are summarized below:
Year of Expiration |  | Number of Warrants |  |  | Weighted Average Exercise Price |
2018 |  |  | 963,153 |  |  | $ | 11.77 |
2019 |  |  | 224,323 |  |  |  | 15.73 |
2020 |  |  | 44,299 |  |  |  | 15.96 |
2022 |  |  | 2,401,233 |  |  |  | 6.10 |
|  |  | 3,633,008 |  |  | $ | 8.32 |

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- Definition Description of equity financings during the periods presented and information related to outstanding warrants of company stock. + References No definition available. + Details
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