Note 2 - Acquisitions - Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		1 Months Ended	9 Months Ended
	Dec. 03, 2019	Dec. 31, 2019	Sep. 30, 2019	Oct. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
Goodwill, Ending Balance		$ 21,993	$ 10,778	$ 10,778	$ 19,817	$ 20,177
Goodwill			$ (26)
Majority Products Business of CUI Power [Member]
Cash and cash equivalents	$ 193	193
Accounts receivable	3,404	3,404
Inventories	4,686	4,686
Other current assets	101	101
Property, plant and equipment	81	81
Right-of-use asset	1,299	1,299
Intangible assets		16,000
Intangible assets		16,000
Total identifiable assets	9,764	25,764
Total identifiable assets		16,000
Accounts payable	(3,599)	(3,599)
Accrued expenses	(879)	(879)
Refund liability	(1,078)	(1,078)
Operating lease liability, current	(230)	(230)
Operating lease liability, long-term	(1,069)	(1,069)
Total liabilities assumed	(6,855)	(6,855)
Net identifiable assets acquired	2,909	18,909
Net identifiable assets acquired		16,000
Goodwill, Ending Balance	29,091	10,287
Goodwill		(18,804)
Net assets acquired	32,000	29,196
Net assets acquired		(2,804)
Payments to Acquire Businesses, Gross	32,000	29,196
Cash paid		(2,804)
Fair value of consideration transferred	$ 32,000	29,196
Fair value of consideration transferred		$ (2,804)