Note 4 - Property and Equipment, Net (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Depreciation and Amortization, Continuing Operations	$ 0.3	$ 0.3	$ 0.3
Property, Plant and Equipment, Disposals	0.2	5.6
Accumulated Depreciation, Depletion and Amortization, Sale or Disposal of Property, Plant and Equipment	$ 0.2	0.8
Proceeds from Sale of Buildings		$ 8.1
Lessor, Operating Lease, Term of Contract		10 years
Deferred Gain on Sale of Building		$ 2.9
Sale of Building, Expenses		$ 0.4

Amount of gain on the sale of building that does not qualify for gain recognition as of the balance sheet date.

No definition available.

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Namespace Prefix:	cui_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deprecation and amortization expense attributable to property, plant and equipment and intangible assets of continuing operations.

+ References

No definition available.

+ Details

Name:	cui_DepreciationAndAmortizationContinuingOperations
Namespace Prefix:	cui_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the expense related to sale of building

+ References

No definition available.

+ Details

Name:	cui_SaleOfBuildingExpenses
Namespace Prefix:	cui_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of decrease in accumulated depreciation, depletion and amortization as a result of sale or disposal of property, plant and equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_AccumulatedDepreciationDepletionAndAmortizationSaleOfPropertyPlantAndEquipment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Term of lessor's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=119202524&loc=SL77919359-209981

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow from sale of buildings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount of divestiture of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration