Revenue - Additional Information (Detail)		1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2016	Dec. 31, 2014 USD ($) Installment	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Revenues [Line Items]
Distribution fees			$ 20,862,000	$ 17,666,000	$ 71,313,000	$ 60,299,000
Long-term trade receivables			200,000		$ 200,000		$ 400,000
Long-term trade credit maintenance services term					1 year
Allowances for doubtful accounts			0		$ 0		$ 0
Deferred revenue, recognized			2,400,000	12,200,000	11,900,000	18,300,000
Company recognized revenue from performance obligations satisfied in a prior period			0		$ 900,000
Minimum
Revenues [Line Items]
Expected long-term trade receivables collection period					3 years
Maximum
Revenues [Line Items]
Expected long-term trade receivables collection period					4 years
Itochu Corporation Agreement
Revenues [Line Items]
Number of installments | Installment		3
Remaining term of distribution agreement	8 years 6 months
Itochu Corporation Agreement | Distribution Rights
Revenues [Line Items]
Distribution fees		$ 4,000,000	$ 100,000	$ 100,000	$ 400,000	$ 400,000