Equity - Schedule of Common Stock Purchase Warrant Activity (Detail) - Warrant - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Warrants, Outstanding, Beginning balance	748,060	748,060
Number of Warrants, Issued	3,166,491	0
Number of Warrants, Cancelled or expired	15,385
Number of Warrants, Exercised	34,615
Number of Warrants, Outstanding, Ending balance		748,060
Weighted Avg. Exercise Price, Outstanding, Beginning balance	$ 5.17	$ 5.17
Weighted Avg. Exercise Price, Issued	4.47	0
Weighted Avg. Exercise Price, Outstanding, Ending balance	$ 4.60	$ 5.17