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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 |  |

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 + Details
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