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BUSINESS COMBINATIONS - Narrative (Details) - business | 6 Months Ended
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Jun. 30, 2020 | Jun. 30, 2019
Business Acquisition [Line Items] |  |
Number of businesses acquired | 4 |
Minimum |  |
Business Acquisition [Line Items] |  |
Useful life of finite lived intangible assets | 5 years |
Maximum |  |
Business Acquisition [Line Items] |  |
Useful life of finite lived intangible assets | 10 years |
Western | Tuck-in Solid Waste Collection Business |  |
Business Acquisition [Line Items] |  |
Number of businesses acquired | 3 |
Resource Solutions | Recycling Operation |  |
Business Acquisition [Line Items] |  |
Number of businesses acquired | 1 |
Eastern | Tuck-in Solid Waste Collection Business |  |
Business Acquisition [Line Items] |  |
Number of businesses acquired |  | 3

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