SIGNIFICANT ACCOUNTING POLICIES (Cash, Cash Equivalents and Uncashed Checks) (Details)	Dec. 31, 2020 USD ($)
Accounting Policies [Abstract]
Bank disbursement account balance	$ 0

Cash and Cash Equivalents, Bank Disbursement Account, Minimum Balance Allowed

No definition available.

Name:	clh_CashAndCashEquivalentsBankDisbursementAccountMinimumBalanceAllowed
Namespace Prefix:	clh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant