Warrants (Detail)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Warrant Exercise Price Range One 4.50
Class of Warrant or Right [Line Items]
Warrants outstanding	5,000
Weighted average remaining contractual life	4 months 6 days
Warrants exercisable	5,000
Weighted average exercise price per share | $ / shares	$ 4.50
Warrant Exercise Price Range Two 9.00
Class of Warrant or Right [Line Items]
Warrants outstanding	1,116,111
Weighted average remaining contractual life	2 years 3 months 11 days
Warrants exercisable	1,116,111
Weighted average exercise price per share | $ / shares	$ 9.00
Warrant Exercise Price Range Three 10.00
Class of Warrant or Right [Line Items]
Warrants outstanding	1,455,555
Weighted average remaining contractual life	3 years 9 months 18 days
Warrants exercisable	1,455,555
Weighted average exercise price per share | $ / shares	$ 10.00
Warrant Exercise Price Range Four 11.00
Class of Warrant or Right [Line Items]
Warrants outstanding	850,000
Weighted average remaining contractual life	4 years 5 months 8 days
Warrants exercisable	850,000
Weighted average exercise price per share | $ / shares	$ 11.00
Warrant Exercise Price Range Five 4.50-11.00
Class of Warrant or Right [Line Items]
Warrants outstanding	3,426,666
Weighted average remaining contractual life	3 years 5 months 16 days
Warrants exercisable	3,426,666
Weighted average exercise price per share | $ / shares	$ 9.91