Note 16 - Working Capital Line of Credit and Overdraft Facility (Details Textual) - Wells Fargo Bank N.A [Member] £ in Thousands, $ in Thousands	Oct. 05, 2016	Sep. 27, 2013	Mar. 31, 2018 USD ($)	Mar. 31, 2018 GBP (£)
Revolving Credit Facility [Member] | CUI, Inc [Member]
Line of Credit Facility, Expiration Period		2 years
Capital Expenditures Exceed Limit			$ 1,750
Line of Credit Facility, Maximum Borrowing Capacity			4,000
Multi-currency Variable Rate Overdraft Facility [Member]
Line of Credit Facility, Expiration Period	5 years
Long-term Line of Credit, Total			837
Line of Credit Facility, Maximum Borrowing Capacity			2,100	£ 1,500
Multi-currency Variable Rate Overdraft Facility [Member] | CUI, Inc [Member]
Long-term Line of Credit, Total			$ 0