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COMMITMENTS AND CONTINGENCIES - Environmental Remediation Liability (Details) - Southbridge Landfill - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2021 | Mar. 31, 2020
Accrual for Environmental Loss Contingencies [Roll Forward] |  |
Beginning balance | $ 4,261 | $ 4,596
Accretion expense | 28 | 30
Obligations incurred | 0 | 27
Obligations settled | 0 | (12)
Ending balance | $ 4,289 | $ 4,641

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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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