Preferred Stock, Common Stock and Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding beginning balance	3,114,371
Options, Granted	1,172,000	829,500
Options, Outstanding ending balance	4,077,259	3,114,371
2007 Plan and 2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding beginning balance	3,114,371
Options, Granted	1,172,000
Options, Exercised	(199,111)
Options, Expired/Forfeited/Exchanged	(10,001)
Options, Outstanding ending balance	4,077,259	3,114,371
Options, Vested and expected to vest at December 31, 2020	4,077,259
Options, Exercisable at December 31, 2020	1,943,106
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price [Roll Forward]
Weighted Average Exercise Price, Outstanding beginning balance	$ 1.71
Weighted Average Exercise Price, Granted	1.58
Weighted Average Exercise Price, Exercised	1.08
Weighted Average Exercise Price, Expired/Forfeited/Exchanged	2.42
Weighted Average Exercise Price, Outstanding ending balance	1.70	$ 1.71
Weighted Average Exercise Price, Vested and expected to vest at December 31, 2020	1.70
Weighted Average Exercise Price, Exercisable at December 31, 2020	$ 2.32
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Remaining Contractual Term [Abstract]
Weighted Average Remaining Contractual Term (Years), Outstanding	8 years 1 month 2 days	8 years 3 months 25 days
Weighted Average Remaining Contractual Term (Years), Granted	9 years 2 months 19 days
Weighted Average Remaining Contractual Term (Years), Exercised	2 years 9 months 10 days
Weighted Average Remaining Contractual Term (Years), Expired/Forfeited/Exchanged	6 years 11 months 4 days
Weighted Average Remaining Contractual Term (Years), Vested and expected to vest at December 31, 2020	8 years 1 month 2 days
Weighted Average Remaining Contractual Term (Years), Exercisable at December 31, 2020	7 years 3 months 25 days
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Aggregate Intrinsic Value [Abstract]
Aggregate Intrinsic Value, Outstanding beginning balance	$ 2,143,756
Aggregate Intrinsic Value, Exercised	484,188
Aggregate Intrinsic Value, Expired/Forfeited/Exchanged	30,620
Aggregate Intrinsic Value, Outstanding ending balance	5,134,768	$ 2,143,756
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2020	5,134,768
Aggregate Intrinsic Value, Exercisable at December 31, 2020	$ 1,967,591