Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current deferred tax assets:
Inventory reserves		$ 537
Accrued expenses		373
Deferred rent		17
Allowance for uncollectible accounts receivable		32
Valuation allowance		(959)
Net current deferred tax asset	$ 0	0
Noncurrent deferred tax assets:
Stock-based compensation	1,543	1,154
Inventory	1,819
Accrued expenses and other	936
Contribution carryforward	2	2
Research credit carryforward	4,224	3,200
Fixed assets	275	278
Capitalized start up costs and other intangibles	3,864	4,233
Net operating loss carryforwards	64,867	51,145
Deferred Tax Assets, Gross	77,530	60,012
Valuation allowance	(75,897)	(60,009)
Net noncurrent deferred tax asset	1,633	3
Noncurrent deferred tax liabilities
Fixed assets	(973)
Purchase accounting intangibles	(16,923)	$ (3)
Net noncurrent deferred tax liability	(17,896)
Net deferred tax asset (liability)	$ (16,263)