SELECTED BALANCE SHEET COMPONENTS - PROPERTY PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Property and equipment, net:
Total property and equipment, gross	$ 12,246		$ 12,246		$ 10,968
Less: Accumulated depreciation	(8,279)		(8,279)		(7,093)
Total, net	3,967		3,967		3,875
Depreciation and amortization	400	$ 400	1,200	$ 1,200
Machinery and equipment
Property and equipment, net:
Total property and equipment, gross	3,264		3,264		3,150
Furniture, fixtures and office equipment
Property and equipment, net:
Total property and equipment, gross	981		981		931
Computer equipment and software
Property and equipment, net:
Total property and equipment, gross	3,485		3,485		3,147
Leasehold improvements
Property and equipment, net:
Total property and equipment, gross	3,908		3,908		3,332
Construction in process
Property and equipment, net:
Total property and equipment, gross	$ 608		$ 608		$ 408