Restructuring Activities - Summary of Charges Related to Restructuring Activities (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost And Reserve [Line Items]
Accrued Restructuring Expenses			$ 66,000	$ 921,000
Expenses	$ 0		0	4,890,000
Less: Payments and Adjustments			(51,000)
Less: Payments		$ (3,800,000)		(4,755,000)
Accrued Restructuring Expenses	15,000	1,056,000	15,000	1,056,000
Severance Benefits and Related Costs Due to Workforce Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Accrued Restructuring Expenses			66,000	921,000
Expenses				4,890,000
Less: Payments and Adjustments			(51,000)
Less: Payments				(4,755,000)
Accrued Restructuring Expenses	$ 15,000	$ 1,056,000	$ 15,000	$ 1,056,000