Stockholders' Equity - Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended			3 Months Ended				9 Months Ended
	Oct. 13, 2021	Oct. 31, 2021	Mar. 31, 2021	Feb. 29, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Feb. 28, 2021	Oct. 02, 2020
Sale of stock
Common stock that can be purchased with warrants (in shares)				1,400,000							450,000
Commission percentage			3.00%
Subsequent event
Sale of stock
Common stock that can be purchased with warrants (in shares)	13,333,324	13,333,324
Common stock that can be purchased with one-half of warrant (in shares)	1	1
2020 Shelf Registration Statement
Sale of stock
Aggregate amount of securities issuable												$ 200,000
At-the-market sales
Sale of stock
Proceeds from issuance of common stock in public offering, net of offering costs									$ 9,266
At-the-market sales | Common stock
Sale of stock
Issuance of common stock (in shares)					1,801,180	4,593,034	520,937		6,915,151
Public offering
Sale of stock
Proceeds from issuance of common stock in public offering, net of offering costs										$ 48,434
Public offering | Common stock
Sale of stock
Issuance of common stock (in shares)				17,250,000				17,250,000
Share price (in dollars per share)				$ 3.00
Proceeds from issuance of common stock in public offering, net of offering costs				$ 48,400
Public offering | Common stock | Subsequent event
Sale of stock
Issuance of common stock (in shares)	26,666,648	26,666,648
Share price (in dollars per share)	$ 0.85	$ 0.85
Proceeds from issuance of common stock in public offering, net of offering costs	$ 21,100	$ 21,100
At The Market Offering | Common stock
Sale of stock
Proceeds from issuance of common stock in public offering, net of offering costs									$ 9,300
Gross Proceeds			$ 50,000