Consolidated Balance Sheets and Statements of Operations and Comprehensive Loss Components - Inventories/Prepaid/PP&E (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Inventories:
Work-in-process	$ 1,612	$ 1,270
Finished goods	154	181
Total	1,766	1,451
Prepaid expenses and other:
Prepaid IC material and production costs	1,107	3
Prepaid insurance	115	116
Prepaid software	38	250
Interest receivable		17
Other	87	87
Total	1,347	473
Property and equipment, net:
Property and equipment, gross	4,774	6,210
Less: Accumulated depreciation and amortization	(3,947)	(4,936)
Property and equipment, net	827	1,274
Equipment, furniture and fixtures and leasehold improvements
Property and equipment, net:
Property and equipment, gross	4,478	5,906
Acquired software
Property and equipment, net:
Property and equipment, gross	$ 296	$ 304