Share-Based Compensation - Summary of Stock Option Activity (Detail) - shares		12 Months Ended
	Jul. 31, 2017	Dec. 31, 2019
Number of Shares
Outstanding as of December 31, 2018		2,297,810
Granted		1,041,734
Exercised		(78,610)
Forfeited or cancelled		(291,506)
Outstanding as of December 31, 2019		2,969,428
2017 Plan [Member]
Number of Shares
Outstanding as of December 31, 2018		2,297,810
Granted	1,154,989	870,434
Exercised		(78,610)
Forfeited or cancelled		(291,506)
Outstanding as of December 31, 2019		2,798,128
2019 Inducement Plan [Member]
Number of Shares
Granted		171,300
Outstanding as of December 31, 2019		171,300