Accounts Receivable and Reserves for Product Sales - Summary of Change in Reserves for Discounts and Allowances (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	$ 306
Provision	3,664
Payments/credits	(1,865)
Balance, as of June 30, 2017	2,105
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	1
Provision	1,413
Payments/credits	(1,173)
Balance, as of June 30, 2017	241
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	238
Provision	1,901
Payments/credits	(405)
Balance, as of June 30, 2017	1,734
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	67
Provision	350
Payments/credits	(287)
Balance, as of June 30, 2017	$ 130