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COMMITMENTS AND CONTINGENCIES - Narrative (Detail) |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 28, 2017 USD ($) | Nov. 30, 2016 basin | Sep. 30, 2018 USD ($) | Dec. 31, 2018 USD ($) executive_officer | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Apr. 26, 2017 USD ($) | Jan. 29, 2016 | Apr. 30, 2011 USD ($) | May 31, 2009 USD ($) | Dec. 20, 2000 a
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Monthly payments (up to) |  |  |  | $ 23,000 |  |  |  |  |  |  |
Total rent expense under operating leases charged to operations |  |  |  | 10,571,000 | $ 12,242,000 | $ 11,437,000 |  |  |  |  |
Number of storm water basins | basin |  | 2 |  |  |  |  |  |  |  |  |
Payments for litigation settlement |  |  |  | $ 850,000 |  |  |  |  |  |  |
Ancillary services period |  |  |  | 5 years |  |  |  |  |  |  |
Litigation settlement, total cash and services |  |  |  | $ 1,200,000 |  |  |  |  |  |  |
Number of executive officers | executive_officer |  |  |  | 5 |  |  |  |  |  |  |
Intangible assets, useful life |  |  |  | 10 years |  |  |  |  |  |  |
Contract extension period |  |  |  | 1 year |  |  |  |  |  |  |
Total annual commitments for salaries |  |  |  | $ 1,821,000 |  |  |  |  |  |  |
Notice of Intent to Sue under the Resource Conservation and Recovery Act |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Agreement in principle amount (up to) |  |  |  |  |  |  | $ 5,000,000 |  |  |  |
Steadfast Insurance Company |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Litigation settlement, amount awarded form other party |  |  | $ 10,000,000 |  |  |  |  |  |  |  |
Minimum |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Initial term of employment contract |  |  |  | 1 year |  |  |  |  |  |  |
Intangible assets, useful life |  |  |  | 5 years |  |  |  |  |  |  |
Salary and bonuses payment range |  |  |  | 1 year |  |  |  |  |  |  |
Minimum | Employment Contracts |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Intangible assets, useful life |  |  |  | 1 year |  |  |  |  |  |  |
Maximum |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Initial term of employment contract |  |  |  | 3 years |  |  |  |  |  |  |
Intangible assets, useful life |  |  |  | 10 years |  |  |  |  |  |  |
Salary and bonuses payment range |  |  |  | 3 years |  |  |  |  |  |  |
Maximum | Employment Contracts |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Intangible assets, useful life |  |  |  | 2 years |  |  |  |  |  |  |
Southbridge Landfill |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Risk free interest rate (as a percent) |  |  |  | 2.60% |  |  |  |  |  |  |
Litigation settlement, total cash and services |  |  |  | $ 1,216,000 | 0 |  |  |  |  |  |
Reserve for probable loss |  |  |  | 226,000 |  |  |  |  |  |  |
Litigation settlement, amount awarded form other party |  |  |  | 10,000,000 | $ 0 |  |  |  |  |  |
Loss on contract termination |  |  |  | $ 8,724,000 |  |  |  |  |  |  |
Potsdam Environmental Remediation Liability |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Risk free interest rate (as a percent) |  |  |  | 1.50% |  |  |  |  |  |  |
Number of acres composing solid waste transfer station (in acres) | a |  |  |  |  |  |  |  |  |  |  | 25
Estimate of total undiscounted costs associated with implementing the preferred remedies |  |  |  |  |  |  |  |  | $ 12,130,000 | $ 10,219,000 |
Remediation activities, participant share percentage |  |  |  |  |  |  |  | 15.00% |  |  |
MADEP | Notice of Intent to Sue under the Resource Conservation and Recovery Act |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Agreement in principle amount (up to) |  |  |  |  |  |  | $ 10,000,000 |  |  |  |
21E Settlement and Water System Construction Funding Agreement | Bonds |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Facility term | 20 years |  |  |  |  |  |  |  |  |  |
21E Settlement and Water System Construction Funding Agreement | Bonds | Maximum |  |  |  |  |  |  |  |  |  |  |
Other Commitments [Line Items] |  |  |  |  |  |  |  |  |  |  |
Anticipated costs | $ 5,000,000 |  |  |  |  |  |  |  |  |  |

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