Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of restricted cash

	As of December 31,
	2017		2016
	(in thousands)
Certificates of deposit	$	5	$	5
Flexible spending funds		3		2
Fixed deposit pledge		173		156
	$	181	$	163

Summary of allowance for doubtful accounts

	Year ended December 31,
	2017			2016
	(in thousands)
Beginning balance	$	31		$	389
Charges to costs and expenses		(20	)		(235	)
Accounts write offs, less recoveries		(4	)		(123	)
Ending balance	$	7		$	31

Schedule of inventories

	As of December 31,
	2017		2016
	(in thousands)
Raw materials	$	476	$	3,112
Work-in-process		2,334		4,251
Finished goods		220		637
	$	3,030	$	8,000

Schedule of property and equipment

	As of December 31,
	2017			2016
	(in thousands)
Machinery, equipment and tooling	$	6,105		$	17,769
Leasehold improvements		4,624			4,624
Information systems		819			991
Furniture and fixtures		8			699
Construction in progress		—			263
Total cost		11,556			24,346
Accumulated depreciation and amortization		(10,741	)		(17,236	)
Property and equipment, net	$	815		$	7,110

Schedule of property and equipment, estimated useful lives

Asset description	Life
Buildings	39 years
Machinery, equipment and tooling	3-10 years
Leasehold improvements	Lesser of life of lease or economic life
Furniture and fixtures	7 years
Information systems	3 years

Schedule of product warranty liability

	Year ended December 31,
	2017			2016
	(in thousands)
Balance, beginning of period	$	27		$	73
Charged to cost of sales		20			(1	)
Actual product warranty expenditures		(32	)		(45	)
Balance, end of period	$	15		$	27

Summary of accumulated comprehensive loss

	Year Ended December 31,
	2017			2016
	(in thousands)
Unrealized loss on investments, net of tax	$	(2	)	$	(12	)
Unrealized loss on currency translation		(1	)		(18	)
Ending balance	$	(3	)	$	(30	)