Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Deferred tax assets:    
Net operating loss carryforwards $ 28,200 $ 18,933
Depreciation and amortization 6,688 7,235
Accrued expenses 1,183 698
Capitalized start-up costs 8,531 7,276
Capitalized R&D   27
Other 259 67
Deferred tax assets before valuation allowance 44,861 34,236
Valuation allowance (43,751) (31,966)
Deferred tax assets, net 1,110 2,270
Deferred tax liabilities    
IPR&D (36) (121)
Change in accounting method (1,074) (2,149)
Total deferred tax liabilities (1,110) (2,270)
Net deferred tax assets $ 0 $ 0