Common Stock	6 Months Ended
Jun. 30, 2020
Equity [Abstract]
Common Stock	5. Common Stock Registered Direct Offering On April 20, 2020, the Company sold 4,787,553 shares at $1.671 per share, pursuant to a securities purchase agreement, dated as of April 16, 2020, by and among the Company and certain institutional investors, for gross proceeds of approximately $8,000 prior to deducting fees and expenses of approximately $686. In a concurrent private placement, the Company issued warrants to purchase an aggregate of up to 4,787,553 shares of its common stock to investors with an exercise price of $1.55 per share and an expiration date of April 20, 2022. In addition, the Company issued warrants to purchase up to 311,191 shares of its common stock to the designees of the placement agent with an exercise price of $2.0888 per share and an expiration date of April 20, 2022. The investor and placement agent warrants have a fair value of approximately $0.64 and $0.54 per share, respectively. Exercise of Warrants During the three months ended June 30, 2020 and 2019, the Company issued 437,999 and 8,277,112 shares of common stock, respectively, upon exercise of warrants to purchase 524,353 and 8,277,112 shares of common stock, respectively. The Company collected proceeds of $536 and $83 upon the exercise of these warrants during the three months ended June 30, 2020 and 2019, respectively. During the six months ended June 30, 2020 and 2019, the Company issued 944,746 and 8,974,612 shares of common stock, respectively, upon exercise of warrants to purchase 1,147,184 and 8,974,612 shares of common stock, respectively. The Company collected proceeds of $775 and $153 upon the exercise of these warrants during the six months ended June 30, 2020 and 2019, respectively. Exercise of Stock Options During the three and six months ended June 30, 2020, stock options to buy 2,500 and 22,497 shares were exercised, respectively, and the Company collected proceeds of $3 and $24, respectively.

Common Stock

6 Months Ended

Jun. 30, 2020

5. Common Stock

Registered Direct Offering

On April 20, 2020, the Company sold 4,787,553 shares at $1.671 per share, pursuant to a securities purchase agreement, dated as of April 16, 2020, by and among the Company and certain institutional investors, for gross proceeds of approximately $8,000 prior to deducting fees and expenses of approximately $686. In a concurrent private placement, the Company issued warrants to purchase an aggregate of up to 4,787,553 shares of its common stock to investors with an exercise price of $1.55 per share and an expiration date of April 20, 2022. In addition, the Company issued warrants to purchase up to 311,191 shares of its common stock to the designees of the placement agent with an exercise price of $2.0888 per share and an expiration date of April 20, 2022. The investor and placement agent warrants have a fair value of approximately $0.64 and $0.54 per share, respectively.

Exercise of Warrants

During the three months ended June 30, 2020 and 2019, the Company issued 437,999 and 8,277,112 shares of common stock, respectively, upon exercise of warrants to purchase 524,353 and 8,277,112 shares of common stock, respectively. The Company collected proceeds of $536 and $83 upon the exercise of these warrants during the three months ended June 30, 2020 and 2019, respectively.

During the six months ended June 30, 2020 and 2019, the Company issued 944,746 and 8,974,612 shares of common stock, respectively, upon exercise of warrants to purchase 1,147,184 and 8,974,612 shares of common stock, respectively. The Company collected proceeds of $775 and $153 upon the exercise of these warrants during the six months ended June 30, 2020 and 2019, respectively.

Exercise of Stock Options

During the three and six months ended June 30, 2020, stock options to buy 2,500 and 22,497 shares were exercised, respectively, and the Company collected proceeds of $3 and $24, respectively.