Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended
	Nov. 05, 2019	Apr. 30, 2020	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019	Nov. 30, 2019
Class of Stock [Line Items]
Net proceeds from sales of common stock				$ 10,250	$ 5,607
Common Stock
Class of Stock [Line Items]
Issuance of common stock, new issues (in shares)				6,825,000	3,825,000
Aspire Capital
Class of Stock [Line Items]
Equity purchase agreement, value	$ 100,000
Common stock issued as commitment fees (in shares)						350,000
Common stock registered for resale (in shares)						31,000,000
Net proceeds from sales of common stock				$ 10,200	$ 5,600
Aspire Capital | Common Stock
Class of Stock [Line Items]
Issuance of common stock, new issues (in shares)				6,825,000	3,825,000
Sale of additional shares at an average price (in dollars per share)				$ 1.50	$ 1.47
Healios
Class of Stock [Line Items]
Common stock issued upon exercise of warrant (in shares)			4,000,000
Common stock issued, price per share (in dollars per share)			$ 1.76
Subsequent Event | Healios
Class of Stock [Line Items]
Proceeds from exercise of warrant		$ 7,000