Income Taxes - Income Tax (Provision) for Federal Statutory Corporate Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Taxes
Tax (provision) at federal statutory rate	$ 1,754	$ 2,152
State income tax benefit (provision), net of federal benefit	318	413
Research and development tax credits	290	250
Foreign earnings or losses taxed at different rates	(27)	12
Tax rate change	(31)	23
Other	67	628
Change in valuation allowance	(2,427)	(9,918)
Benefit/(provision) for income taxes	$ (56)	$ (6,440)