ACCRUED EXPENSES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued insurance, employee medical insurance costs	$ 18.6	$ 9.4
Accrual loss for workers' compensation, comprehensive general liability and vehicle liability self-insurance programs	$ 82.8	$ 65.6

Accrual For Workers' Compensation, Comprehensive General Liability And Vehicle Liability Self-insurance Programs

No definition available.

Name:	clh_AccrualForWorkersCompensationComprehensiveGeneralLiabilityAndVehicleLiabilitySelfInsurancePrograms
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant