Restructuring - Schedule of Components of Outstanding Restructuring Liabilities (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Restructuring expenses	$ 1,492,000	$ 0	$ 0
Cash payments	(1,299,000)
Employee Severance And Other Benefits [Member] | Accrued Expenses and Other Current Liabilities [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses	1,492,000
Cash payments	(1,299,000)
Liability included in accrued expenses and other current liabilities at December 31, 2019	$ 193,000