SIGNIFICANT ACCOUNTING POLICIES (Remedial Liabilities and Revenue Recognition) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) site numberOfSource	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Regulatory Liabilities [Line Items]
Accrual for Environmental Loss Contingencies | $	$ 114,813	$ 114,173	$ 121,017
Period of time over which business acquisitions have been acquired (in years)	18 years
Safety-Kleen
Regulatory Liabilities [Line Items]
Number of sources of revenue	2
Environmental Services
Regulatory Liabilities [Line Items]
Number of sources of revenue	3
Minimum
Regulatory Liabilities [Line Items]
Remedial liabilities at acquisition, risk-free interest rate (as a percent)	1.37%
Maximum
Regulatory Liabilities [Line Items]
Remedial liabilities at acquisition, risk-free interest rate (as a percent)	4.90%
Superfund Proceedings
Regulatory Liabilities [Line Items]
Superfund sites | site	130