Note 2 - Acquisition (Details Textual) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 03, 2019	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Goodwill, Ending Balance		$ 22,873	$ 22,873	$ 21,993
Business Combination, Acquisition Related Costs		200	200
CUI Power [Member]
Revenue from Contract with Customer, Including Assessed Tax				$ 32,000
Majority Products Business of CUI Power [Member]
Payments to Acquire Businesses, Gross	$ 29,200
Goodwill, Ending Balance	$ 10,900
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		10,900	29,800
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual		$ 1,400	$ 4,600