Stockholders' Equity - Schedule of Warrants Outstanding (Details) - Warrants to purchase common stock - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Number of Shares
Outstanding at beginning of period (in shares)	357,010
Exercised (in shares)	(3,400)
Outstanding at end of period (in shares)	353,610	357,010
Exercisable (in shares)	353,610
Weighted- average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 9.78
Exercised (in dollars per share)	10.00
Outstanding at end of period (in dollars per share)	9.78	$ 9.78
Exercisable (in dollars per share)	$ 9.78
Weighted- average Remaining Contractual Term (years)
Outstanding	4 years 10 months 6 days	5 years 6 months 26 days
Exercisable	4 years 10 months 6 days
Aggregate Intrinsic Value
Outstanding	$ 2,857	$ 4,708
Exercisable	$ 2,857