Stockholders’ Equity (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 12, 2018	Mar. 15, 2017	Sep. 08, 2016	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Common Stock
Common stock, shares issued						14,265,411		10,633,042
Issuance of common stock (in shares)				3,592,858
Gross proceeds				$ 25,150
Offering costs						$ 2,093	$ 1,257
Follow On Offering
Common Stock
Issuance of common stock (in shares)	3,142,858
Net proceeds	$ 23,100
Offering costs						$ 2,100
Share price (in dollars per share)	$ 7.00
Private placement
Common Stock
Issuance of common stock (in shares)		1,324,256
Price per issue and sold units		$ 9.47
Gross proceeds		$ 12,500			$ 8,979
Number of shares per unit		1
Number of warrants per unit		0.75
Net proceeds		$ 11,300
Offering costs								$ 1,300
Overallotment
Common Stock
Issuance of common stock (in shares)	450,000		27,755
Share price (in dollars per share)			$ 10.00