Income Taxes - Schedule of Reconciliation of Effective Tax Rate of Provision for Income Taxes Differs from Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	34.00%
State tax	8.10%	5.50%	1.80%
Stock compensation	9.80%	0.50%	(1.70%)
Permanent items	(1.00%)	0.50%	(0.10%)
Credits	6.10%	2.70%	2.70%
TCJA change in federal rate			(58.40%)
Other	0.30%	0.10%	(0.60%)
Change in valuation allowance	(44.30%)	(30.30%)	22.30%
Total	0.00%	0.00%	0.00%