Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Registered Direct Offerings On February 12, 2021, we entered into a Securities Purchase Agreement (the “Institutional Purchase Agreement”) with certain institutional investors (the “Institutional Purchasers”). Pursuant to the terms of the Institutional Purchase Agreement, we sold to the Institutional Purchasers in a registered direct offering an aggregate of 24,906,134 shares of our common stock and warrants to purchase an aggregate of 12,453,067 shares of our common stock at a combined purchase price equal to $2.45 per share and associated warrant. Each warrant features an exercise price equal to $2.90 per share, is exercisable immediately upon issuance and will expire five years from the issuance date. Additionally, in a concurrent non-brokered registered direct offering, we entered into a Securities Purchase Agreement (the “Additional Purchase Agreement”) with certain accredited investors (the “Additional Purchasers”). Pursuant to the terms of the Additional Purchase Agreement, we sold to the Additional Purchasers an aggregate of 1,632,652 shares of our common stock and warrants to purchase an aggregate of 816,326 shares of our common stock at a combined purchase price equal to $2.45 per share and associated warrant. Each warrant features an exercise price equal to $2.90 per share, is exercisable immediately upon issuance and will expire five years from the issuance date. The closing of the offerings occurred on February 17, 2021. In connection with the registered direct offerings, we received net proceeds of approximately $60.7 million. Sales Pursuant to Common Stock Sales Agreement On February 12, 2021, we suspended the use of the at-the-market transactions facility (the “ATM”) and terminated the continuous offering pursuant to the Common Stock Sales Agreement (“Sales Agreement”) entered into in February 2018 with H.C. Wainwright & Co., LLC (“HCW”). In accordance with the terms of the Sales Agreement, we could offer and sell shares of our common stock having an aggregate offering price of up to $25.0 million from time to time through HCW pursuant to the ATM program. As of February 12, 2021, we had sold an aggregate of 3,784,912 shares of our common stock pursuant to the Sales Agreement for aggregate gross proceeds of $9.5 million. We will no longer make any sales of our common stock pursuant to the Sales Agreement unless and until a new prospectus supplement is filed with the Securities and Exchange Commission. Private Placement Offering On January 21, 2021, the Company entered into a securities purchase agreement (the “January Private Placement”) with certain investors (the “January Purchasers”). Pursuant to the terms of the January Private Placement, the Company agreed to sell to the January Purchasers an aggregate of 12,500,000 shares of its common stock at a purchase price equal to $2.00 per share, along with warrants to purchase an aggregate of 6,250,000 shares of its common stock. In connection with the January Private Placement, the Company received gross proceeds of $25.0 million. Each warrant is exercisable for one share of common stock and features an exercise price equal to $2.90 per share. The warrants are exercisable immediately upon issuance and will expire five and one-half years from the issuance date. Warrant Exercises Subsequent to December 31, 2020 the company issued 801,148 shares of common stock for net proceeds of $1.8 million in connection with warrant exercises associated with the April Purchase Agreement and May Purchase Agreement.