Stockholders' Equity - 2019 Stock Offerings (Details) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Jan. 06, 2020	Dec. 23, 2019	Jun. 30, 2020	Jun. 30, 2019
Class of Stock [Line Items]
Proceeds from common stock offering			$ 2,973	$ 0
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