SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	SIGNIFICANT ACCOUNTING POLICIES The Company's significant accounting policies are described in Note 2, "Significant Accounting Policies," in the Company's Annual Report on Form 10-K for the year ended December 31, 2017. There have been no material changes in these policies or their application except for the changes described below. Changes in Reporting Segments During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment. See Note 18, "Segment Reporting," for more information. The amounts presented for the three and nine months ended September 30, 2017 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on the consolidated statements of operations, consolidated statements of comprehensive income, consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented. Recent Accounting Pronouncements Standards implemented In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). On January 1, 2018, the Company adopted Topic 606 using the modified retrospective method for all contracts. Results for reporting periods beginning on the date of adoption are presented under ASC 606, while prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 605, Revenue Recognition. Upon adoption, a cumulative effect adjustment was not required as the majority of the Company’s contracts are recognized based on time and materials incurred and were not impacted by the new guidance. The Company has concluded that the most significant impact of the standard relates to the incremental disclosures required. In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The Company adopted the amendment on a modified retrospective basis effective January 1, 2018. As a result of adoption, the Company recorded a cumulative effect adjustment that reduced retained earnings by $1.6 million. In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendment requires an employer to report the service cost component of net benefit cost in the same line item as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. In addition, the amendment allows only the service cost component to be eligible for capitalization when applicable. The Company adopted the amendment in the first quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendment better aligns an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The Company adopted the amendment in the third quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements. Standards to be implemented The Company is evaluating the impact that the below standards to be implemented will have on the Company's consolidated financial statements. In February 2016, FASB issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In February 2018, FASB issued ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842. The amendment clarifies that land easements are within the scope of the new leases standard (ASC 842) and introduces a new transition practical expedient allowing a company to not assess whether existing and expired land easements that were not previously accounted for as leases under current US GAAP (ASC 840) are or contain leases under ASC 842. In July 2018, FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendment provides improvements that clarify specific aspects of the guidance in ASU 2016-02. In August 2018, FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements. The amendment provides entities with an additional (and optional) transition method to adopt the new leases standard and provides lessors with a practical expedient, by class of underlying asset, to not separate nonlease components from the associated lease component and, instead, to account for those components as a single component if certain criteria are met. The Company will adopt the new standard beginning on January 1, 2019. While the Company is still continuing to assess the effect of adoption, it expects that the new standard will have a material effect on its consolidated balance sheet related to the recognition of new assets and lease liabilities. In preparation for the adoption of the guidance, the Company is in the process of implementing new software, testing and validating the data in the new software and changing controls and processes to enable the preparation of financial information.

SIGNIFICANT ACCOUNTING POLICIES

The Company's significant accounting policies are described in Note 2, "Significant Accounting Policies," in the Company's Annual Report on Form 10-K for the year ended December 31, 2017. There have been no material changes in these policies or their application except for the changes described below.

Changes in Reporting Segments

During the first quarter of fiscal year 2018, certain of the Company's businesses undertook a reorganization which included changes to the underlying business and management structures. The reorganization resulted in combining the Environmental Services businesses from an operational and management perspective and is expected to deepen customer relationships and allow for efficiencies across the Company's operations through the sharing of resources, namely labor and equipment which will reduce third party spend and promote the cross selling of such business offerings. In connection with this reorganization, the Company’s chief operating decision maker also requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. These changes required a reconsideration of the Company’s operating segments in the first quarter of 2018 and resulted in a change in the Company’s assessment of its operating segments. Upon reconsideration of the identification of the Company’s operating segments, the Company concluded that there are now two operating segments for disclosure in accordance with ASC 280 Segment reporting; (i) the Environmental Services segment which consists of the Company’s historical Technical Services, Industrial Services, Field Services and Oil, Gas and Lodging businesses and (ii) the Safety-Kleen segment. See Note 18, "Segment Reporting," for more information. The amounts presented for the three and nine months ended September 30, 2017 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on the consolidated statements of operations, consolidated statements of comprehensive income, consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented.

Recent Accounting Pronouncements

Standards implemented

In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which replaces numerous requirements in U.S. GAAP, including industry-specific requirements, and provides companies with a single revenue recognition model for recognizing revenue from contracts with customers. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective method). On January 1, 2018, the Company adopted Topic 606 using the modified retrospective method for all contracts. Results for reporting periods beginning on the date of adoption are presented under ASC 606, while prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 605, Revenue Recognition. Upon adoption, a cumulative effect adjustment was not required as the majority of the Company’s contracts are recognized based on time and materials incurred and were not impacted by the new guidance. The Company has concluded that the most significant impact of the standard relates to the incremental disclosures required.

In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The Company adopted the amendment on a modified retrospective basis effective January 1, 2018. As a result of adoption, the Company recorded a cumulative effect adjustment that reduced retained earnings by $1.6 million.

In March 2017, the FASB issued ASU 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendment requires an employer to report the service cost component of net benefit cost in the same line item as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. In addition, the amendment allows only the service cost component to be eligible for capitalization when applicable. The Company adopted the amendment in the first quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements.

In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendment better aligns an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The Company adopted the amendment in the third quarter of 2018. Adoption did not have a material impact on the Company's consolidated financial statements.

Standards to be implemented

The Company is evaluating the impact that the below standards to be implemented will have on the Company's consolidated financial statements.

In February 2016, FASB issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. In February 2018, FASB issued ASU 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842. The amendment clarifies that land easements are within the scope of the new leases standard (ASC 842) and introduces a new transition practical expedient allowing a company to not assess whether existing and expired land easements that were not previously accounted for as leases under current US GAAP (ASC 840) are or contain leases under ASC 842. In July 2018, FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendment provides improvements that clarify specific aspects of the guidance in ASU 2016-02. In August 2018, FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements. The amendment provides entities with an additional (and optional) transition method to adopt the new leases standard and provides lessors with a practical expedient, by class of underlying asset, to not separate nonlease components from the associated lease component and, instead, to account for those components as a single component if certain criteria are met. The Company will adopt the new standard beginning on January 1, 2019. While the Company is still continuing to assess the effect of adoption, it expects that the new standard will have a material effect on its consolidated balance sheet related to the recognition of new assets and lease liabilities. In preparation for the adoption of the guidance, the Company is in the process of implementing new software, testing and validating the data in the new software and changing controls and processes to enable the preparation of financial information.