Distribution Agreement - Additional Information (Detail) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2016 USD ($)	Dec. 31, 2014 USD ($) Installment	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Marketing Agreement [Line Items]
Customer deposits			$ 20,920		$ 20,920		$ 19,400
Deferred revenue			14,088		14,088		10,433
Distribution rights revenue			118	$ 59	356	$ 59
Distribution Rights
Marketing Agreement [Line Items]
Deferred revenue			3,466		3,466		$ 3,822
Itochu Corporation Agreement
Marketing Agreement [Line Items]
Distribution agreement term		10 years
Distribution fees		$ 4,000
Number of installments | Installment		3
Remaining term of distribution agreement	8 years 6 months
Distribution rights revenue			$ 118	$ 59	$ 356	$ 59
Itochu Corporation Agreement | Distribution Rights
Marketing Agreement [Line Items]
Deferred revenue	$ 4,000
Itochu Corporation Agreement | First Installment
Marketing Agreement [Line Items]
Distribution fees		$ 1,000
Customer deposits		1,000
Itochu Corporation Agreement | Second Installment
Marketing Agreement [Line Items]
Distribution fees		1,000
Customer deposits								$ 1,000
Itochu Corporation Agreement | Third Installment
Marketing Agreement [Line Items]
Distribution fees		$ 2,000
Customer deposits	$ 2,000