Income Taxes - Summary of Company's Net Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Intangibles, including acquired in-process research and development	$ 2,035	$ 2,151
Capitalized start-up costs	785	830
Net operating loss carryforwards	13,751	4,653
Research and development credit carryforwards	1,873	418
Deferred revenue	1,193
Equity-based compensation	1,940
Accruals and allowances		211
Gross deferred tax assets	21,577	8,263
Deferred tax asset valuation allowance	(20,549)	(7,452)
Total deferred tax assets	1,028	811
Deferred tax liabilities:
Deferred revenue		(811)
Accrual and allowances	(1,028)
Total deferred tax liabilities	(1,028)	(811)
Net deferred tax asset (liability)	$ 0	$ 0