CLOSURE AND POST-CLOSURE LIABILITIES - Changes in Post-Closure Liabilities (Details) $ in Thousands	9 Months Ended
Sep. 30, 2025 USD ($)
Changes to post-closure liabilities
Beginning balance	$ 129,788
Measurement period adjustments from prior period acquisitions	420
New asset retirement obligations	2,838
Accretion	7,851
Changes in estimates recorded to consolidated statement of operations	844
Changes in estimates recorded to consolidated balance sheet	890
Expenditures	(3,466)
Currency translation and other	177
Ending balance	139,342
Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	59,400
Measurement period adjustments from prior period acquisitions	0
New asset retirement obligations	2,838
Accretion	3,739
Changes in estimates recorded to consolidated statement of operations	467
Changes in estimates recorded to consolidated balance sheet	0
Expenditures	(2,496)
Currency translation and other	123
Ending balance	64,071
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	70,388
Measurement period adjustments from prior period acquisitions	420
New asset retirement obligations	0
Accretion	4,112
Changes in estimates recorded to consolidated statement of operations	377
Changes in estimates recorded to consolidated balance sheet	890
Expenditures	(970)
Currency translation and other	54
Ending balance	$ 75,271

Asset Retirement Obligation Changes Recorded in Balance Sheet

No definition available.

Name:	clh_AssetRetirementObligationChangesRecordedInBalanceSheet
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of change in the asset retirement obligation, during the current period, for changes in estimates recorded in the statement of income.

+ References

No definition available.

+ Details

Name:	clh_AssetRetirementObligationChangesRecordedInStatementOfIncome
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Asset Retirement Obligation, Measurement Period Adjustments From Prior Period Acquisitions

+ References

No definition available.

+ Details

Name:	clh_AssetRetirementObligationMeasurementPeriodAdjustmentsFromPriorPeriodAcquisitions
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Asset Retirement Obligation, Payments

+ References

No definition available.

+ Details

Name:	clh_AssetRetirementObligationPayments
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481999/410-20-25-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481850/410-20-50-1

+ Details

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481879/410-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481850/410-20-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

+ Details

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

- Definition

Amount of foreign currency translation gain (loss) which decreases (increases) asset retirement obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481850/410-20-50-1

+ Details

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

- Definition

Amount of asset retirement obligations incurred during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 410
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481850/410-20-50-1

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Details

Name:	clh_ClosureAndPostClosureLiabilitiesAxis=clh_LandfillRetirementLiabilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	clh_ClosureAndPostClosureLiabilitiesAxis=clh_NonLandfillRetirementLiabilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: