Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2018

Accounting Policies [Abstract]

Summary of allowance for doubtful accounts

	June 30, 2018			December 31, 2017
	(in thousands)
Beginning balance	$	7		$	31
Charges to costs and expenses		(2	)		(20	)
Accounts charged off, less recoveries		—			(4	)
Ending balance	$	5		$	7

Schedule of inventories

	June 30, 2018		December 31, 2017
	(in thousands)
Raw materials	$	476	$	476
Work-in-process		2,109		2,334
Finished goods		203		220
	$	2,788	$	3,030

Schedule of property and equipment

	June 30, 2018			December 31, 2017
	(in thousands)
Machinery, equipment and tooling	$	5,435		$	6,105
Leasehold improvements		4,624			4,624
Information systems		819			819
Furniture and fixtures		8			8
Total cost		10,886			11,556
Accumulated depreciation and amortization		(10,474	)		(10,741	)
Property and equipment, net	$	412		$	815