Income Taxes - Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Allowance for doubtful accounts	$ 18	$ 11	$ 15
Accrued expenses and other reserves	2,244	2,082	1,960
Tax credits, deferred R&D, and other	122	44	87
Net operating loss	5,384	6,871	3,989
Valuation allowance	(7,768)	(9,008)	(6,051)
Net deferred tax assets	$ 0	$ 0	$ 0