Derivative Instrument, Annual Extension Period

No definition available.

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Period Type:	duration

- Definition

Derivative Instrument, Decrease in Nonmonetary Notional Amount, Shares

+ References

No definition available.

+ Details

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Namespace Prefix:	cls_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative, Shares, Notional Amount

+ References

No definition available.

+ Details

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Namespace Prefix:	cls_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Derivative, Weighted Average Price Per Share

+ References

No definition available.

+ Details

Name:	cls_DerivativeWeightedAveragePricePerShare
Namespace Prefix:	cls_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Long Term Debt, Unhedged, Amount

+ References

No definition available.

+ Details

Name:	cls_LongTermDebtUnhedgedAmount
Namespace Prefix:	cls_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481544/470-10-50-6

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow provided by derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 23
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 14
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

+ Details

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

- Details

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- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cls_TermALoanMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cls_TermBLoanMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_TotalReturnSwapMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cls_InterestRateSwapDecember2025Member
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Balance Type:
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- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
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- Details

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- Details

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- Details

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FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		3 Months Ended		27 Months Ended
	Mar. 14, 2025	Mar. 31, 2025	Mar. 31, 2024	Mar. 13, 2025
Line of Credit Facility [Line Items]
Proceeds from TRS settlement		$ 98.6	$ 32.3
Line of Credit
Line of Credit Facility [Line Items]
Long-term debt, unhedged amount		516.8
Revolving Facility \| Line of Credit
Line of Credit Facility [Line Items]
Long-term debt, unhedged amount		150.0
Term A Loan \| Secured Debt \| Line of Credit
Line of Credit Facility [Line Items]
Long-term debt, unhedged amount		110.6
Term B Loan \| Secured Debt \| Line of Credit
Line of Credit Facility [Line Items]
Long-term debt, unhedged amount		$ 256.2
Total Return Swap (TRS)
Line of Credit Facility [Line Items]
Derivative instrument, annual extensions period		1 year
Derivative instrument, decrease in nonmonetary notional amount (in shares)			1,250
Proceeds from TRS settlement	$ 98.6
Derivative notional amount (in shares)		1,250
Weighted average price per share (in USD per share)	$ 91.58			$ 12.73
Interest Rate Swap December 2025 \| Term A Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		$ 130.0
Interest Rate Swap December 2025 \| Term B Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		200.0
Interest Rate Swap December 2025 to June 2027 \| Term A Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		80.0
Interest Rate Swap December 2025 to June 2027 \| Term B Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		50.0
Interest Rate Swap June 2027 to June 2029 \| Term A Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		40.0
Interest Rate Swap June 2027 to June 2029 \| Term B Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		150.0
Interest Rate Swap March 2025 to June 2027 \| Term B Loan \| Designated as Hedging Instrument
Line of Credit Facility [Line Items]
Notional amount		$ 40.0