Schedule of Net Deferred Tax Assets (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax asset (liability)
Net operating loss carryforwards	$ 46,305,000	$ 41,152,000	$ 27,999,000
Non-deductible accrued expenses	422,000	245,000	248,000
Right of use asset	(138,000)
Lease liability	264,000
Deferred rent		148,000	49,000
Deferred revenue			38,000
Stock compensation expense	1,472,000	899,000	387,000
Depreciation differences	(94,000)	(125,000)	(18,000)
Disallowed interest expense	99,000
Charitable contributions	4,000	6,000	6,000
Valuation allowance	(56,206,000)	(49,563,000)	(32,670,000)
Federal
Deferred tax asset (liability)
Net operating loss carryforwards	46,200,000
Tax credits	7,249,000	6,481,000	3,437,000
State
Deferred tax asset (liability)
Net operating loss carryforwards	150,000
Tax credits	$ 623,000	$ 757,000	$ 524,000