Note 2 - Summary of Significant Accounting Policies (Details Textual) £ in Thousands				3 Months Ended					12 Months Ended
		Jan. 01, 2018 USD ($)	May 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($) shares		Mar. 31, 2016 USD ($)	Dec. 31, 2018 USD ($) shares		Dec. 31, 2017 USD ($) shares		Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Mar. 13, 2019 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 GBP (£)	Sep. 30, 2015	Mar. 31, 2014
Net Income (Loss) Attributable to Parent, Total									$ (17,325,000)		$ (12,589,000)		$ (7,266,000)
Net Cash Provided by (Used in) Operating Activities, Total									(12,283,000)		(9,369,000)		(601,000)
Retained Earnings (Accumulated Deficit), Ending Balance		$ (106,668,000)		$ (123,993,000)		$ (108,559,000)			(123,993,000)		(108,559,000)
Working Capital				16,900,000					16,900,000
Cash, Uninsured Amount				300,000					300,000
Cash, FDIC Insured Amount						900,000					900,000
Cash and Cash Equivalents in Foreign Accounts				68,000		200,000			68,000		200,000
Restricted Cash, Noncurrent				523,000					523,000
Proceeds from Collection of Notes Receivable									19,000		39,000
Investment in Convertible Note Receivable, Noncurrent				655,000					655,000
Allowance for Doubtful Accounts Receivable, Current, Ending Balance				167,000		135,000			167,000		135,000
Inventory Valuation Reserves, Ending Balance				2,495,000		946,000			2,495,000		946,000
Asset Impairment Charges, Total									1,509,000
Reclassified Deposits and Other Assets to Prepaid Assets				100,000					100,000
Asset Impairment Charges, Other than Goodwill											0		0
Goodwill and Intangible Asset Impairment, Total			$ 0						4,347,000		3,155,000
Goodwill, Impairment Loss				3,100,000	$ 1,300,000	3,200,000			4,347,000		3,152,000		0	$ 0
Accrued Liabilities, Current, Total				4,851,000		4,186,000			4,851,000		4,186,000
Employee-related Liabilities, Current, Total				1,700,000		1,900,000			1,700,000		1,900,000
Accounts Payable, Trade, Current				1,700,000		1,300,000			1,700,000		1,300,000
Derivative, Gain on Derivative									129,000		111,000		113,000
Payments for Derivative Instrument, Financing Activities									$ 227,000
Number of Categories in Product Offerings									2
Concentration Risk, Percentage									100.00%		100.00%		100.00%
Revenue from Contract with Customer, Including Assessed Tax									$ 96,789,000		$ 83,275,000		$ 86,461,000
Standard and Extended Product Warranty Accrual, Ending Balance				37,000		40,000			37,000		40,000
Advertising Expense									2,000,000		1,800,000		1,700,000
Advertising Costs Offset Against Revenue									$ 600,000		$ 300,000		$ 300,000
Stock Issued During Period, Shares, Issued for Services | shares									1,844		63,602		25,811
Number of Operating Segments									6
Number of Reportable Segments									3
Operating Leases Future Minimum Payments Due, Present Value				7,800,000					$ 7,800,000
Shipping and Handling [Member]
Revenue from Contract with Customer, Including Assessed Tax									$ 27,000		$ 17,000		$ 23,000
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Distributor One [Member]
Concentration Risk, Percentage											26.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Three Distributor Arrangements [Member]
Concentration Risk, Percentage											15.00%
Transferred at Point in Time [Member]
Percentage of Revenue From Goods and Services									84.00%
Revenue from Contract with Customer, Including Assessed Tax									$ 80,838,000
Accounting Standards Update 2014-09 [Member]
Retained Earnings (Accumulated Deficit), Ending Balance						1,891,000					$ 1,891,000
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		1,900,000
Interest Rate Swap [Member]
Payments for Derivative Instrument, Financing Activities									$ 227,000
Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life									20 years	[1]	20 years
Deposits and Other Assets [Member]
Asset Impairment Charges, Total				1,500,000
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life									10 years
SEC Schedule, 12-09, Reserve, Inventory [Member]
Inventory Valuation Reserves, Ending Balance				2,495,000		946,000			$ 2,495,000		$ 946,000		774,000	$ 483,000
Energy Segment [Member]
Goodwill and Intangible Asset Impairment, Total									4,347,000		3,152,000
Goodwill, Impairment Loss									4,347,000		3,152,000
Revenue from Contract with Customer, Including Assessed Tax									20,342,000
Energy Segment [Member] | Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax									$ 4,391,000
Energy Segment [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(0.90)
Energy Segment [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life	[2],[3]								20 years
Energy Segment [Member] | SEC Schedule, 12-09, Reserve, Inventory [Member]
Inventory Valuation Reserves, Ending Balance				1,400,000					$ 1,400,000
Power and Electromechanical Segment [Member]
Goodwill and Intangible Asset Impairment, Total											3,000
Goodwill, Impairment Loss
Revenue from Contract with Customer, Including Assessed Tax									76,447,000
Power and Electromechanical Segment [Member] | Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax									$ 76,447,000
Power and Electromechanical Segment [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 2,800,000
Power and Electromechanical Segment [Member] | Maximum [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life	[3]								20 years
Other Segments [Member]
Goodwill and Intangible Asset Impairment, Total
Goodwill, Impairment Loss
Revenue from Contract with Customer, Including Assessed Tax									725,000
Other Depreciation and Amortization									900,000		700,000		500,000
Test Products International Inc. [Member]
Note Receivable Interest Rate								5.00%
Investment Income, Interest									17,000		18,000		19,000
Royalty Expense									10,000		16,000		37,000
Proceeds from Collection of Notes Receivable									19,000		39,000
Financing Receivable, Net, Total				318,000		330,000			318,000		330,000
Financing Receivable, Allowance for Credit Losses, Ending Balance						$ 0					$ 0
VPS [Member]
Investment in Convertible Note Receivable, Noncurrent				655,000					655,000
Test Products International Inc. [Member]
Notes Receivable, Related Parties								$ 400,000
Test Products International Inc. [Member]
Business Acquisition Number of Shares Owned in Equity Method | shares						352,589					352,589
Equity Method Investment, Ownership Percentage																		8.50%	8.94%
JAPAN
Cash, Uninsured Amount				300,000		$ 100,000			300,000		$ 100,000
Europe [Member]
Cash, Uninsured Amount				1,000		100,000			1,000		100,000
Revenue from Contract with Customer, Including Assessed Tax									19,815,000
Europe [Member] | Energy Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax									15,620,000
Europe [Member] | Power and Electromechanical Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax									4,195,000
CANADA
Cash, Uninsured Amount				67,000		100,000			67,000		100,000
Mortgage Note Payable [Member]
Secured Debt, Total				0		$ 3,350,000	[4]		0		$ 3,350,000	[4]
Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member]
Retained Earnings (Accumulated Deficit), Ending Balance																$ 2,900,000
Wells Fargo Bank N.A [Member] | Multi-currency Variable Rate Overdraft Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity				52,021,000					52,021,000								£ 1,344
CUI Inc And CUI Canada [Member] | Bank of America [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity															$ 10,000,000
CUI, Inc [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match											6.00%
Defined Benefit Plan, Plan Assets, Contributions by Employer									500,000		$ 400,000		400,000
CUI, Inc [Member] | Wells Fargo Bank N.A [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Remaining Borrowing Capacity				2,000,000					2,000,000
CUI, Inc [Member] | Wells Fargo Bank N.A [Member] | Multi-currency Variable Rate Overdraft Facility [Member]
Line of Credit Facility, Remaining Borrowing Capacity				$ 600,000					600,000
Orbital [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match											5.00%
Defined Benefit Plan, Plan Assets, Contributions by Employer									$ 300,000		$ 200,000		$ 300,000

[1] Technology rights are amortized over a 20-year life or the term of the rights agreement.

[2] All intangibles are reviewed annually for impairment, or sooner if circumstances change.

[3] Technology rights include $1.0 million of capitalized costs that are related to our CUI-Canada acquisition in March 2015. The CUI-Canada technology rights are amortized over a 7-year life. The rest of the technology rights are amortized over a 20-year life.

[4] On October 1, 2013, the funding of the purchase of the Company's Tualatin, Oregon corporate offices from Barakel, LLC was completed. The purchase price for this asset was $5.1 million. The purchase was funded, in part, by a promissory note payable to Wells Fargo Bank in the amount of $3.7 million plus interest at the rate of 2% above LIBOR, payable over ten years with a balloon payment due at maturity. It was secured by a deed of trust on the purchased property, which was executed by CUI Properties, LLC and guaranteed by CUI Global, Inc. During 2018 and 2017, the Company made principal payments of approximately $3.4 million and $89 thousand, respectively, against the mortgage promissory note payable. In December 2018, this note was paid off as part of a sale-leaseback transaction. At December 31, 2017, the balance owed on the mortgage promissory note payable was $3.4 million of which $94 thousand and $3.3 million were in current and long-term liabilities, respectively.