Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jun. 26, 2018	Jul. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Aug. 08, 2017	Dec. 31, 2016	Dec. 31, 2015
Preferred stock, shares authorized			50,000,000	50,000,000
Preferred stock, shares issued			0	0
Preferred stock, shares outstanding			0	0
Common stock, shares authorized			750,000,000	750,000,000
Common stock, par value (in dollars per share)			$ 0.0001	$ 0.0001
Common stock, shares issued			62,082,348	54,040,000
Common stock, shares outstanding			62,082,348	54,040,000
Issuance of common stock in exchange for commitment to provide debt financing				$ 2,448
Stock price (in dollars per share)					$ 8.16
Issuance of common stock upon exercise of warrants (in shares)	332,896
Issuance of common stock upon exercise of warrants			$ 6,762
July 2018 Offering
Common stock, shares issued		4,500,000
Stock issued (in dollars per share)		$ 20
Option for additional shares
Common stock, shares issued		675,000
July 2018 Offering inclusive of option for additional shares
Proceeds from issuance of common stock		$ 97,300
Payment of offering costs		$ 500
Common stock
Common stock, shares issued			62,083,000	54,040,000		52,665,000	50,346,000
Issuance of common stock in exchange for commitment to provide debt financing (in shares)				300,000
Issuance of common stock upon exercise of warrants (in shares)			333,000