OTHER ITEMS AND CHARGES (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Unusual or Infrequent Items, or Both [Abstract]
Expense from acquisition activities	$ 1,019	$ 1,632	$ 3,062	$ 2,046

The aggregate amount of expense associated with legal, consulting and other similar costs recognized during the accounting period associated with the acquisition and integration of acquired businesses or select development projects

No definition available.

Name:	cwst_ExpenseFromAcquisitionActivities
Namespace Prefix:	cwst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration