Restructuring - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Research and Development Expense [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 100,000
General and Administrative Expense [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 200,000
Restructuring Plan, July 2018 [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges incurred			$ 7,400,000
Amounts accrued		$ 0	0
Restructuring Plan, November 6, 2018 [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges incurred			$ 1,600,000
Amounts accrued		$ 0