Details of Certain Financial Statement Components and Supplemental Disclosures of Cash Flow Information and Non-Cash Activities - Components of Property and Equipment (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 13,181,000	$ 13,181,000
Less: accumulated depreciation and amortization	(12,948,000)	(12,172,000)
Property and Equipment, Net	233,000	1,009,000
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	11,911,000	11,911,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	1,065,000	1,065,000
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 205,000	$ 205,000