Debt - Narrative (Details) - USD ($) $ in Millions	Sep. 19, 2025	Dec. 31, 2025
Short-Term Debt [Line Items]
Target asset coverage ratio		200.00%
Reduced average coverage rate		167.50%
Asset coverage ratio		246.80%
SPV Credit Facility
Short-Term Debt [Line Items]
Line of credit facility committed loan	$ 150
Line of credit facility uncommitted loan	$ 150
Basis spread on variable rate	1.95%
Line of credit facility, commitment fee percentage	0.50%
SPV Credit Facility \| One-Month Anniversary
Short-Term Debt [Line Items]
Line of credit facility, commitment fee percentage	0.10%
SPV Credit Facility \| Two Month Anniversary
Short-Term Debt [Line Items]
Line of credit facility, commitment fee percentage	0.20%
SPV Credit Facility \| Three Month Anniversary
Short-Term Debt [Line Items]
Line of credit facility, commitment fee percentage	0.35%

Investment Company, Senior Security Indebtedness, Asset Coverage Ratio, Reduced Target Percentage

No definition available.

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- Definition

Investment Company, Senior Security Indebtedness, Asset Coverage Ratio, Target Percentage, Minimum

+ References

No definition available.

+ Details

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- Definition

Line Of Credit Facility, Committed Loan Amount

+ References

No definition available.

+ Details

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

- Definition

Line Of Credit Facility, Uncommitted Loan Amount

+ References

No definition available.

+ Details

Name:	cls_LineOfCreditFacilityUncommittedLoanAmount
Namespace Prefix:	cls_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
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Period Type:	duration

- Definition

Percentage of total assets less all liabilities and indebtedness not represented by senior security, to senior security representing indebtedness.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Investment Company Act of 1940
-Section 61
-Paragraph a
-Subparagraph (1)
-Publisher SEC

+ Details

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- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Period Type:	duration

- 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

No definition available.

+ Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
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Period Type:

- Details

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Namespace Prefix:
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- Details

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