Income Taxes - Summary of Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Net operating loss carryforwards	$ 45,488	$ 46,749
Research and development credit carryforwards	3,355	2,462
Accruals and other	2,079	1,385
Capitalized license and organization costs	61	66
Capitalized start-up costs	246	278
Depreciation	0	21
Total gross deferred tax asset	51,229	50,961
Deferred tax liabilities:
IPR&D	16,335	0
Property and equipment	189	0
Total gross deferred tax liabilities	(16,524)	0
Valuation allowance	(51,040)	(50,961)
Net deferred tax liability	$ (16,335)	$ 0