PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation expense, inclusive of landfill and finance lease amortization	$ 64.6	$ 65.4

Depreciation Expense, Inclusive Of Landfill And Finance Lease Amortization

No definition available.

Name:	clh_DepreciationExpenseInclusiveOfLandfillAndFinanceLeaseAmortization
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration