Income Taxes - Schedule of Significant Components of Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 25,418	$ 9,987
Accruals and reserves	1,816	1,123
Deferred Rent	3,300	3,494
Other deferred tax assets	51	36
Stock based compensation	2,871
Deferred revenue	3,264	1,721
Research credit	3,322	543
Total deferred tax assets	40,042	16,904
Less valuation allowance	(36,208)	(13,041)
Net deferred tax assets	3,834	3,863
Deferred tax liabilities:
Depreciation	(3,785)	(3,791)
Intangible assets	(49)	(59)
Other deferred tax liabilities	(22)	(31)
Total deferred tax liabilities	(3,856)	(3,881)
Long term deferred taxes, liabilities	$ (22)	$ (18)