Income Taxes - Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
(Decrease) increase in income taxes resulting from:
Income tax benefit at Federal statutory income tax rate	$ (4,203)	$ (2,314)
State income tax (benefit) expense, net of federal benefit	(610)	172
State research and development, investment credits	71	(397)
Non-deductible meals & entertainment	36	26
Non-deductible stock compensation expense	18	6
GILTI	0	577
Nontaxable interest income	0	2
Foreign tax rate differential	(4)	(22)
Federal research and development credits	(490)	(378)
Uncertain tax positions	(110)	53
Provision to tax return adjustments	21	513
Change in tax rates	0	(3)
Change in valuation allowance	934	2,127
Foreign research and development incentives	0	(5)
Loss on legal entity dissolution	244	0
Other	90	(11)
Income tax (benefit) expense	$ (4,003)	$ 346