Stockholders' Equity	6 Months Ended
Jun. 30, 2019
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Equity Distribution Agreement On July 30, 2019, the Company entered into the Sales Agreement with Canaccord, as agent, pursuant to which the Company may offer and sell shares of common stock, for aggregate gross sale proceeds of up to $30,000,000 from time to time through Canaccord. Upon delivery of a placement notice based on the Company’s instructions and subject to the terms and conditions of the Sales Agreement, Canaccord may sell the shares by methods deemed to be an “at the market” offering, in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing market prices, or by any other method permitted by law, including negotiated transactions, subject to the prior written consent of the Company. The Company is not obligated to make any sales of shares under the Sales Agreement. The Company or Canaccord may suspend or terminate the offering of shares upon notice to the other party, subject to certain conditions. Canaccord will act as sales agent on a commercially reasonable efforts basis consistent with its normal trading and sales practices and applicable state and federal law, rules and regulations and the rules of Nasdaq. The Company has agreed to pay Canaccord for its services of acting as agent 3% of the gross proceeds from the sale of the shares pursuant to the Sales Agreement. The Company has also agreed to provide Canaccord with customary indemnification for certain liabilities. At June 30, 2019, legal and accounting fees associated with the Sales Agreement were immaterial. Legal and accounting fees are expected to be reclassified to share capital upon issuance of shares under the Sales Agreement. Purchase Agreement On July 29, 2019, the Company entered into a $30,000,000 Purchase Agreement with Lincoln Park, pursuant to which the Company may sell and issue to Lincoln Park, and Lincoln Park is obligated to purchase, up to $30,000,000 in value of its shares of common stock from time to time over a 36-month period starting from the effective date of the respective registration statement. The Company may direct Lincoln Park, at its sole discretion, and subject to certain conditions, to purchase up to 200,000 shares of common stock on any business day, provided that at least one business day has passed since the most recent purchase. The amount of a purchase may be increased under certain circumstances provided, however, that Lincoln Park’s committed obligation under any single purchase shall not exceed $2,000,000. The purchase price of shares of common stock related to the future funding will be based on the then prevailing market prices of such shares at the time of sales as described in the Purchase Agreement. Public Offering On June 4, 2018, the Company sold 7,015,000 shares of its common stock in a public offering at $7.50 per share, for an aggregate gross cash purchase price of $52.6 million, resulting in net proceeds of $49.2 million after underwriters discount and expenses.

Stockholders' Equity

6 Months Ended

Jun. 30, 2019

7. Stockholders’ Equity

Equity Distribution Agreement

On July 30, 2019, the Company entered into the Sales Agreement with Canaccord, as agent, pursuant to which the Company may offer and sell shares of common stock, for aggregate gross sale proceeds of up to $30,000,000 from time to time through Canaccord.

Upon delivery of a placement notice based on the Company’s instructions and subject to the terms and conditions of the Sales Agreement, Canaccord may sell the shares by methods deemed to be an “at the market” offering, in negotiated transactions at market prices prevailing at the time of sale or at prices related to such prevailing market prices, or by any other method permitted by law, including negotiated transactions, subject to the prior written consent of the Company. The Company is not obligated to make any sales of shares under the Sales Agreement. The Company or Canaccord may suspend or terminate the offering of shares upon notice to the other party, subject to certain conditions. Canaccord will act as sales agent on a commercially reasonable efforts basis consistent with its normal trading and sales practices and applicable state and federal law, rules and regulations and the rules of Nasdaq.

The Company has agreed to pay Canaccord for its services of acting as agent 3% of the gross proceeds from the sale of the shares pursuant to the Sales Agreement. The Company has also agreed to provide Canaccord with customary indemnification for certain liabilities. At June 30, 2019, legal and accounting fees associated with the Sales Agreement were immaterial. Legal and accounting fees are expected to be reclassified to share capital upon issuance of shares under the Sales Agreement.

Purchase Agreement

On July 29, 2019, the Company entered into a $30,000,000 Purchase Agreement with Lincoln Park, pursuant to which the Company may sell and issue to Lincoln Park, and Lincoln Park is obligated to purchase, up to $30,000,000 in value of its shares of common stock from time to time over a 36-month period starting from the effective date of the respective registration statement.

The Company may direct Lincoln Park, at its sole discretion, and subject to certain conditions, to purchase up to 200,000 shares of common stock on any business day, provided that at least one business day has passed since the most recent purchase. The amount of a purchase may be increased under certain circumstances provided, however, that Lincoln Park’s committed obligation under any single purchase shall not exceed $2,000,000. The purchase price of shares of common stock related to the future funding will be based on the then prevailing market prices of such shares at the time of sales as described in the Purchase Agreement.

Public Offering

On June 4, 2018, the Company sold 7,015,000 shares of its common stock in a public offering at $7.50 per share, for an aggregate gross cash purchase price of $52.6 million, resulting in net proceeds of $49.2 million after underwriters discount and expenses.