Warrants Outstanding (Detail)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Class of Warrant or Right [Line Items]
Weighted Average Per Share Intrinsic Value, Outstanding | $ / shares	$ 0
Weighted Average Per Share Intrinsic Value, Warrants assumed in the Merger | $ / shares	0.94
Weighted Average Per Share Intrinsic Value, Granted | $ / shares	0
Weighted Average Per Share Intrinsic Value, Exercised | $ / shares	0
Weighted Average Per Share Intrinsic Value, Cancelled | $ / shares	0
Weighted Average Per Share Intrinsic Value, Outstanding | $ / shares	$ 14.25
Number of warrants, Outstanding | shares
Number of warrants, Warrants assumed in the Merger | shares	1,898,541
Number of warrants, Granted | shares	1,750,000
Number of warrants, Exercised | shares	0
Number of warrants, Cancelled | shares	0
Number of warrants, Outstanding | shares	3,648,541