Schedule of Stock Options Activity (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Employee Stock Option [Member]
Shares
Beginning balance	1,141,040
Options granted	155,000
Options exercised	(426,990)
Options expired/forfeited	(9,000)
Ending balance	860,050	1,141,040
Options exercisable	860,050
Weighted Average Exercise Price
Beginning balance	$ 3.95
Options granted	9.85
Options exercised	4.27
Options expired/forfeited	3.41
Ending balance	5.17	$ 3.95
Options exercisable	$ 5.17
Weighted Average Remaining Contractual Term (Years)
Options outstanding	4 years 7 months 13 days	5 years 9 months 14 days
Options exercisable	4 years 7 months 13 days
Aggregate Intrinsic Value
Beginning Balance	$ 19.81
Options exercised	15.83
Ending balance	16.90	$ 19.81
Options exercisable	$ 16.90
Allied Pacific of California [Member]
Shares
Beginning balance	853,800
Options granted	0
Options exercised	0
Options expired/forfeited	0
Ending balance	853,800	853,800
Options exercisable	853,800
Weighted Average Exercise Price
Beginning balance	$ 0.167
Options granted	0
Options exercised	0
Options expired/forfeited	0
Ending balance	0.167	$ 0.167
Options exercisable	$ 0.167
Weighted Average Remaining Contractual Term (Years)
Options outstanding	1 year	1 year 9 months
Options exercisable	1 year
Aggregate Intrinsic Value
Beginning Balance	$ 508,864
Ending balance	508,864	$ 508,864
Options exercisable	$ 508,864