Net Loss Per Share - Schedule of Anti-dilutive Weighted-Average Equity Instruments Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	37,825,715	4,294,701
Awards under Equity Incentive Plan [Member]
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	4,403,792	3,295,666
Nonvested Restricted Shares and Restricted Stock Units [Member]
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	290,125	130,000
Warrants to Purchase Common Stock [Member]
Earnings Per Share Basic [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	33,131,798	869,035