Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Allowance for doubtful accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 155		$ 478		$ 199
Charged to Costs & Expenses	[1]	662		267		279
Deductions	[1]	(733)		(590)
Balance at End of Period		84		155		478
Allowance for chargebacks and other deductions
Valuation and Qualifying Accounts Disclosure [Line Items]
Charged to Costs & Expenses	[2]	3,834
Deductions	[2]	(123)
Balance at End of Period		3,711
Reserve for excess and obsolete inventory
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		929		839
Charged to Costs & Expenses		544		175		839
Deductions		(470)	[3]	(85)	[2]
Balance at End of Period		1,003		929		839
Deferred tax asset valuation allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		62,308		31,400		12,512
Charged to Other Accounts	[4]	(1,929)		30,908		18,888
Balance at End of Period		$ 60,379		$ 62,308		$ 31,400

[1] Increases in the allowance for doubtful accounts consist of our provision for bad debts, which is included within selling, general, and administrative expenses on the consolidated statements of operations and comprehensive loss. Decreases in the allowances for doubtful accounts consist of the write-off of specific accounts and the recovery of previously reserved receivables.

[2] Increases in the allowance for chargebacks and other deductions consist of our provision for chargebacks, cash discounts, returns, fees, and other credits, which are a deduction from product sales on the consolidated statements of operations and comprehensive loss. Decreases in the allowances for chargebacks and other deduction consist of the collection of the underlying accounts and advances received on chargebacks.

[3] Increases in the reserve for excess and obsolete inventory are charged to expense within cost of sales on the consolidated statements of operations and comprehensive loss and are based on the difference, if any, between the cost of the inventory and market, based upon assumptions about future demand. Decreases in the reserve for excess and obsolete inventory consist of the write-off of specific items.

[4] Increases and decreases in the valuation allowance for deferred income tax assets offset the increases and decreases in our gross deferred tax assets, based on the expected realization of those future tax benefits.