Note 8 - Leases (Details Textual) $ in Thousands			3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 01, 2020 USD ($)	Apr. 08, 2019 USD ($) ft²	Dec. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 22, 2020 ft²	Jan. 23, 2020	Mar. 31, 2019
Operating Lease, Right-of-Use Asset, Amortization Expense							$ 1,294	$ 1,251
Operating Lease, Impairment Loss			$ 612				612
Mansfield, Massachusetts [Member]
Lessee, Operating Lease, Renewal Term (Month)		3 years 120 days
Increase in Operating Lease Liabilities and Right-of-Use Assets, Non-cash		$ 1,811
Operating Lease, Increase in Area (Square Foot) | ft²		6,100
Lease Agreement, EMS Facility in Fremont, California [Member]
Lessee, Operating Lease, Renewal Term (Month)										5 years 30 days
Increase in Operating Lease Liabilities and Right-of-Use Assets, Non-cash					$ 1,176		1,176
Lease Agreement, EMS Facility in Mt. Laurel, New Jersey [Member]
Lessee, Operating Lease, Renewal Term (Month)									10 years
Increase in Operating Lease Liabilities and Right-of-Use Assets, Non-cash							2,051
Area of Real Estate Property (Square Foot) | ft²									33,650
Lease Agreement, Ambrell’s Netherlands Facility [Member]
Lessee, Operating Lease, Renewal Term (Month)	3 years
Increase in Operating Lease Liabilities and Right-of-Use Assets, Non-cash	$ 133						133
Decrease In Operating Lease Liabilities and Right-of-Use Assets, Non-cash				$ 48				48
Automobile Leases [Member]
Increase in Operating Lease Liabilities and Right-of-Use Assets, Non-cash			$ 91				$ 91
Lease Agreement, Ambrell’s U.K [Member]
Lessee, Operating Lease, Term of Contract (Year)											15 years
Decrease In Operating Lease Liabilities and Right-of-Use Assets, Non-cash						$ 486		$ 486