Note 8 - Working Capital Line of Credit and Overdraft Facility (Details Textual) £ in Thousands				12 Months Ended
		Mar. 13, 2019 USD ($)	Oct. 05, 2016	Dec. 31, 2018 USD ($)	Dec. 31, 2018 GBP (£)
Multi-currency Variable Rate Overdraft Facility [Member] | Wells Fargo Bank N.A [Member]
Line of Credit Facility, Expiration Period			5 years
Line of Credit Facility, Maximum Borrowing Capacity				$ 52,021,000	£ 1,344
Multi-currency Variable Rate Overdraft Facility [Member] | Wells Fargo Bank [Member]
Guarantor Obligations, Current Carrying Value				2,000,000
Increase (Decrease) in Outstanding Checks, Financing Activities				27,000
Line of Credit Facility, Maximum Borrowing Capacity	[1]			$ 5,000,000
Debt Instrument, Basis Spread on Variable Rate				2.25%
Revolving Credit Facility [Member] | Wells Fargo Bank N.A [Member] | CUI, Inc [Member]
Capital Expenditures Exceed Limit				$ 1,750,000
Revolving Credit Facility [Member] | Bank of America [Member] | CUI Inc And CUI Canada [Member] | Subsequent Event [Member]
Line of Credit Facility, Sub Limit Borrowing Capacity		$ 3,000,000
Line of Credit Facility, Maximum Borrowing Capacity		$ 10,000,000
Revolving Credit Facility [Member] | Bank of America [Member] | CUI Inc And CUI Canada [Member] | Subsequent Event [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate		2.00%

[1] $2 million of the line of credit is reserved to guarantee the obligation of Orbital Gas Systems, Ltd. under its Overdraft Facility.