Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total gross assets	$ 268	$ 268
Less accumulated depreciation	(257)	(238)
Total furniture and fixtures, equipment and leasehold improvements	11	30
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total gross assets	226	226
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total gross assets	36	36
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total gross assets	$ 6	$ 6