Commitments and Contingencies (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2017	Sep. 30, 2017 USD ($) ft²	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) ft²	Sep. 30, 2016 USD ($)
Product Warranty [Abstract]
Period of warranty				12 months
Change in warranty accrual [Roll Forward]
Beginning accrued warranty and related costs		$ 130	$ 330	$ 251	$ 497
Accruals for warranties issued		7	3	77	26
Adjustments related to pre-existing warranties including expirations and changes in estimates		18	(57)	(114)	(188)
Cost of warranty repair		(17)	(10)	(76)	(69)
Ending accrued warranty and related costs		$ 138	$ 266	$ 138	$ 266
Leases [Abstract]
Area of property under long-term operating lease (in square feet) | ft²		19,467		19,467
Additional years per lease option				3 years
Number of additional years to lease term	3 years
Term of royalty agreement				8 years
Aggregate amount payable towards royalty		$ 7,000		$ 7,000
Operating leases
Less than 1 year		202		202
1-3 years		350		350
4-5 years		93		93
More than 5 years		6		6
Total		651		651
Royalty agreement
Less than 1 year		575		575
1-3 years		144		144
Total		719		719
Total
Less than 1 year		777		777
1-3 years		494		494
4-5 years		93		93
More than 5 years		6		6
Total		1,370		1,370
Dingxing
Leases [Abstract]
Total investment agreement value		90,000		90,000
Kazuo
Leases [Abstract]
Total investment agreement value		$ 15,000		$ 15,000