Provision for Income Taxes - Schedule of Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Federal and state net operating loss carryforwards	$ 16,076	$ 11,101
Research and development credits carryforwards	5,087	2,706
Depreciation	3,942	3,489
Deferred Revenue	3,909
Other	1,724	1,292
Total deferred tax assets	30,738	18,588
Less valuation allowance	$ (30,738)	$ (18,588)