Accounts Receivable and Reserves for Product Sales - Summary of Change in Reserves for Discounts and Allowances (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	$ 306
Provision	996
Payments/credits	(322)
Balance, as of March 31, 2017	980
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	1
Provision	256
Payments/credits	(152)
Balance, as of March 31, 2017	105
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	238
Provision	608
Payments/credits	(88)
Balance, as of March 31, 2017	758
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	67
Provision	132
Payments/credits	(82)
Balance, as of March 31, 2017	$ 117