Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended	9 Months Ended
	Feb. 29, 2016	Sep. 30, 2018
Loss Contingencies [Line Items]
Unconditional purchase commitment aggregate amount	$ 1,062,500	$ 404,000
Unconditional purchase commitment payment terms		Quarterly
Unconditional purchase commitment period		May 31, 2020
Minimum [Member]
Loss Contingencies [Line Items]
Unconditional purchase commitment, quarterly payment amount	$ 62,500