Stock-Based Compensation - Summary of Recognized Compensation Cost Related to Stock-Based Compensation Activity (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 332,141	$ 645,899	$ 967,949	$ 1,872,245
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	139,544	153,997	403,453	386,791
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 192,597	$ 491,902	$ 564,496	$ 1,485,454