Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands		2 Months Ended	12 Months Ended
	Feb. 06, 2019	Feb. 28, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Events
Par value of common stock (in dollars per share)			$ 0.001	$ 0.001
Additional common stock issued			$ 8,363	$ 8,036
Subsequent Events
Subsequent Events
Common stock per unit	1
Warrants per common stock	0.5
Common Stock
Subsequent Events
Number of shares issued			577,195	480,480
Additional common stock issued			$ 1
Common Stock | Subsequent Events
Subsequent Events
Number of shares issued	4,000,000
Proceeds from public offering, net of issuance costs	$ 18,500	$ 20,500
Par value of common stock (in dollars per share)	$ 0.001
Exercise price of warrants (in dollars per share)	$ 6.25
Number of warrants issued	2,000,000
Warrants price (in dollars per unit)	$ 5.00
Additional common stock issued	$ 20,000
ATM | Common Stock
Subsequent Events
Number of shares issued			577,195
Share price (in dollars per share)			$ 15.27
Proceeds from public offering, net of issuance costs			$ 8,400
Additional common stock issued			$ 8,800
ATM | Cowen | Common Stock | Subsequent Events
Subsequent Events
Number of shares issued		353,746
Share price (in dollars per share)		$ 5.96
Proceeds from public offering, net of issuance costs		$ 2,000
Additional common stock issued		$ 2,100