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v3.20.2

REVENUES - Narrative (Details) | 6 Months Ended
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Jun. 30, 2020
Revenue from Contract with Customer [Abstract] |
Contract liability, recognition period | 3 months

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- Definition Contract With Customer, Liability, Recognition In Subsequent Period + References No definition available. + Details
Name: | clh_ContractWithCustomerLiabilityRecognitionInSubsequentPeriod
Namespace Prefix: | clh_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_RevenueFromContractWithCustomerAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration