Note 1 - Nature of Operations, Basis of Presentation and Company Conditions (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Number of Subsidiaries in Reportable Segments			3
Number of Categories in Product Offerings			2
Net Income (Loss) Attributable to Parent, Total	$ (1,534)	$ (1,902)	$ (9,561)	$ (7,324)
Net Cash Provided by (Used in) Operating Activities, Total			(9,953)	$ (5,761)
Retained Earnings (Accumulated Deficit), Ending Balance	(116,229)		(116,229)		$ (106,668)	$ (108,559)
Working Capital	16,200		16,200
Revolving Credit Facility [Member] | Wells Fargo Bank N.A [Member] | CUI, Inc [Member]
Line of Credit Facility, Remaining Borrowing Capacity	3,300		3,300
Multi-currency Variable Rate Overdraft Facility [Member] | Wells Fargo Bank N.A [Member]
Line of Credit Facility, Remaining Borrowing Capacity	$ 700		$ 700
Power and Electromechanical and Energy Segments [Member]
Number of Reportable Segments			2