Common Stock	3 Months Ended
Mar. 31, 2019
Preferred Stock Common Stock And Warrants [Abstract]
Common Stock	11. Common Stock Common Stock Outstanding As of March 31, 2019, there were 65,020,320 shares of our common stock outstanding. On November 3, 2017, we entered into an At Market Sales Agreement (“2017 ATM Agreement”) with Cowen and Company, LLC (“Cowen”) under which we may offer and sell from time to time at our sole discretion, shares of our common stock having an aggregate offering price up to $150 million through Cowen as our sales agent. We pay Cowen a commission of up to 3% of the gross sales proceeds of any common stock sold through Cowen under the 2017 ATM Agreement. For the three months ended March 31, 2019, we received net cash proceeds of $13.6 million resulting from sales of 1,343,337 shares of our common stock. As of March 31, 2019, we have $118.9 million remaining under the 2017 ATM Agreement. Subsequent to March 31, 2019 and through May 3, 2019, we sold 43,569 shares of common stock for net proceeds of $0.3 million under the 2017 ATM Agreement.

Common Stock

3 Months Ended

Mar. 31, 2019

Preferred Stock Common Stock And Warrants [Abstract]

11. Common Stock

Common Stock Outstanding

As of March 31, 2019, there were 65,020,320 shares of our common stock outstanding.

On November 3, 2017, we entered into an At Market Sales Agreement (“2017 ATM Agreement”) with Cowen and Company, LLC (“Cowen”) under which we may offer and sell from time to time at our sole discretion, shares of our common stock having an aggregate offering price up to $150 million through Cowen as our sales agent. We pay Cowen a commission of up to 3% of the gross sales proceeds of any common stock sold through Cowen under the 2017 ATM Agreement. For the three months ended March 31, 2019, we received net cash proceeds of $13.6 million resulting from sales of 1,343,337 shares of our common stock. As of March 31, 2019, we have $118.9 million remaining under the 2017 ATM Agreement. Subsequent to March 31, 2019 and through May 3, 2019, we sold 43,569 shares of common stock for net proceeds of $0.3 million under the 2017 ATM Agreement.