Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Noncurrent deferred tax assets:
Stock-based compensation	$ 2,300	$ 1,543
Inventory	204	1,819
Accrued expenses and other	564	936
Contribution carryforward		2
Research credit carryforward	4,970	4,224
Fixed assets	557	275
Capitalized start-up costs and other intangibles	3,586	3,864
Net operating loss carryforwards	82,298	64,867
Deferred Tax Assets, Gross	94,479	77,530
Valuation allowance	(91,885)	(75,897)
Net noncurrent deferred tax asset	2,594	1,633
Noncurrent deferred tax liabilities
Fixed assets	(292)	(973)
Purchase accounting intangibles	(12,699)	(16,923)
Net noncurrent deferred tax liability	(12,991)	(17,896)
Net deferred tax asset (liability)	$ (10,397)	$ (16,263)