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

Contract With Customer, Liability, Recognition In Subsequent Period

No definition available.

Name:	clh_ContractWithCustomerLiabilityRecognitionInSubsequentPeriod
Namespace Prefix:	clh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration