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COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Liability Associated with Southbridge Landfill (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Accrual for Environmental Loss Contingencies [Roll Forward] |  |
Ending balance | $ 10,787 |
Southbridge Landfill |  |
Accrual for Environmental Loss Contingencies [Roll Forward] |  |
Beginning balance | 5,936 | $ 0
Accretion expense | 152 | 82
Obligations incurred | 0 | 6,379
Obligations settled | (915) | (525)
Ending balance | $ 5,173 | $ 5,936

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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 + Details
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