Warrants - Summary of Warrant Activity (Detail) - Warrants Not Settleable in Cash [Member] - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Class of Warrant or Right [Line Items]
Number of Warrants, Outstanding, Beginning balance	1,426,622
Number of Warrants, Granted	45,769,746
Number of Warrants, Exercised	(5,204,495)
Number of Warrants, Outstanding, Ending balance	41,991,873	1,426,622
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 1.81
Weighted Average Exercise Price, Granted	1.00
Weighted Average Exercise Price, Exercised	1.00
Weighted Average Exercise Price, Outstanding, Ending balance	$ 1.03	$ 1.81
Weighted Average Remaining Contractual Life, Outstanding	2 years 8 months 19 days	2 years 2 months 13 days
Weighted Average Remaining Contractual Life, Granted	2 years 9 months 4 days
Weighted Average Fair Value, Outstanding, Beginning balance	$ 1.54
Weighted Average Fair Value, Granted	0.22
Weighted Average Fair Value, Outstanding, Ending balance	$ 0.27	$ 1.54