Income Taxes - Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Research and development credits	$ 2,763	$ 2,054
Other credits	487	378
Operating loss carry forwards	17,249	13,974
Inventories	254	282
Allowance for doubtful accounts	116	321
Depreciation	382	400
Deferred research and development expenses for income tax	240	327
Non-cash compensation	1,120	1,176
Other	921	410
Total gross deferred tax assets	23,532	19,322
Valuation allowance	(23,091)	(18,856)
Net deferred tax assets	441	466
Deferred tax liabilities:
Other identifiable intangible assets	(634)	(825)
Total gross deferred tax liabilities	(634)	(825)
Net deferred tax liabilities	$ (193)	$ (359)