Stockholders' Equity - 2019 Stock Offerings (Details) - USD ($) $ / shares in Units, $ in Thousands				9 Months Ended
	Jan. 06, 2020	Dec. 23, 2019	Aug. 02, 2019	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Proceeds from common stock offering				$ 2,973	$ 63,250
Common Stock Issued December 2019
Class of Stock [Line Items]
Issuance of stock, net (in shares)		10,000,000
Price per share in sale of stock (in dollars per share)		$ 2.75
Proceeds from common stock offering		$ 27,500
Proceeds from issuance of common stock, net		$ 25,344
Over-Allotment Option
Class of Stock [Line Items]
Issuance of stock, net (in shares)	1,081,184
Proceeds from common stock offering	$ 2,973
Proceeds from issuance of common stock, net	$ 2,766
Additional shares of common stock offered in common stock offering (in shares)		1,500,000
August 2019 Offering
Class of Stock [Line Items]
Issuance of stock, net (in shares)			31,625,000
Price per share in sale of stock (in dollars per share)			$ 2.00
Proceeds from common stock offering			$ 63,250
Additional shares of common stock offered in common stock offering (in shares)			4,125,000
Sale of stock, issuance costs			$ 4,384