Leases - Supplemental Balance Sheet Related to Finance Leases (Detail) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Property and equipment, at cost	$ 100,000
Accumulated amortization	(39,000)
Property and equipment, net	61,000
Other current liabilities – finance lease current portion	$ 52,000
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent
Other long-term liabilities	$ 12,000
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Total finance lease liabilities	$ 64,000	$ 0