Warrants - Summary of Warrant Activity (Detail) - Warrants Not Settleable in Cash [Member] - $ / shares	6 Months Ended	12 Months Ended
	Jun. 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	44,819,746
Number of Warrants, Outstanding, Ending balance	46,246,368	1,426,622
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 1.81
Weighted Average Exercise Price, Granted	1.00
Weighted Average Exercise Price, Outstanding, Ending balance	$ 1.02	$ 1.81
Weighted Average Remaining Contractual Life, Outstanding	2 years 6 months 29 days	2 years 2 months 12 days
Weighted Average Remaining Contractual Life, Granted	2 years 7 months 10 days
Weighted Average Fair Value, Outstanding, Beginning balance	$ 1.54
Weighted Average Fair Value, Granted	0.20
Weighted Average Fair Value, Outstanding, Ending balance	$ 0.29	$ 1.54