Goodwill, Identifiable Intangible Assets, and Other Long-Lived Assets	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Identifiable Intangible Assets, and Other Long-Lived Assets	Goodwill, Identifiable Intangible Assets, and Other Long-Lived Assets Goodwill In connection with our acquisition of businesses, we have recorded goodwill, which represents the excess of the consideration transferred over the fair value of the net tangible and identifiable intangible assets acquired. Goodwill is not amortized but instead allocated to its respective reporting unit and evaluated for impairment annually, or more frequently if events or circumstances indicate that the carrying amount of goodwill may be impaired. We have determined that our reporting units are consistent with the reportable segments identified in Note 15 - Segment Information of the notes to consolidated financial statements. Absent any earlier identified impairment indicators, we perform our annual goodwill impairment assessment on October 1 each fiscal year. Qualitative indicators that may trigger the need for interim quantitative impairment testing include, among others, deterioration in macroeconomic conditions, declining financial performance, deterioration in the operational environment, or an expectation of selling or disposing of a portion of a reporting unit. Additionally, an interim impairment test may be triggered by a significant change in business climate, a loss of a significant customer, increased competition, or a sustained decrease in share price. In assessing whether our goodwill is impaired, we compare the fair value of the reporting unit to its carrying amount, including goodwill. If the fair value exceeds the carrying amount, no impairment is recognized. However, if the carrying amount of the reporting unit exceeds the fair value, the goodwill of the reporting unit is impaired and an impairment loss in the amount of the excess is recognized and charged to operations. We did not identify any impairment indicators during the three and six months ended June 30, 2021 that would necessitate an interim impairment assessment of our goodwill. However, our operations were significantly impacted by the COVID-19 pandemic starting with the second quarter of 2020. During the same period, the demand for oil and other refined products significantly deteriorated as a result of the pandemic and the corresponding preventative measures taken around the world to mitigate the spread of the virus, including various local, state, and national jurisdictional “shelter-in-place” orders. Further, other macroeconomic events during such period, including geopolitical tensions between the Organization of Petroleum Exporting Countries (OPEC) and Russia, resulted in a significant drop in the price of crude oil. These negative factors created significant volatility and uncertainty in the markets in which our United States industrial services segment operates, resulting in a significant decrease in the demand for our service offerings. Consequently, in the second quarter of 2020, we revised our near-term revenue and operating margin expectations for such segment and concluded that a triggering event had occurred which indicated that it was more likely than not that its fair value was less than its carrying amount. Accordingly, we performed a quantitative impairment test and determined the fair value of our United States industrial services segment using an income approach whereby fair value was calculated utilizing discounted estimated future cash flows, assuming a risk-adjusted industry weighted average cost of capital. Such weighted average cost of capital was developed with the assistance of an independent third-party valuation specialist and reflected the overall level of inherent risk within the business and the rate of return a market participant would expect to earn as of that date. Cash flow projections were derived from internal forecasts of anticipated revenue growth rates and operating margins, updated for the events discussed above, with cash flows beyond the discrete forecast period estimated using a terminal value calculation which incorporated historical and forecasted trends, an estimate of long-term growth rates, and assumptions about the future demand for our services. Based on the outcome of our second quarter 2020 interim goodwill impairment test, we concluded that the carrying amount of our United States industrial services segment exceeded its fair value, resulting in the recognition of a non-cash goodwill impairment charge of $225.5 million, which was included within our results of operations for the three and six months ended June 30, 2020. We did not identify impairment indicators related to any other reporting unit that would have required an interim impairment assessment. Additionally, we subsequently (as of October 1, 2020) performed our annual impairment assessment of all reporting units and determined there was no incremental impairment of goodwill. NOTE 7 Goodwill, Identifiable Intangible Assets, and Other Long-Lived Assets - (Continued) Due to the inherent uncertainties involved in making estimates, our assumptions may change in future periods. Estimates and assumptions made for purposes of our goodwill impairment testing may prove to be inaccurate predictions of the future, and other factors used in assessing fair value, such as the weighted average cost of capital, are outside the control of management. Unfavorable changes in certain key assumptions may affect future testing results. Significant adverse changes to external market conditions or our internal forecasts, if any, could result in future goodwill impairment charges. It is not possible at this time to determine if any future impairment charge will result or, if it does, whether such a charge would be material to our results of operations. Identifiable Intangible Assets and Other Long-Lived Assets Our identifiable intangible assets, arising out of the acquisition of businesses, include contract backlog, developed technology/vendor network, customer relationships, and certain subsidiary trade names, all of which are subject to amortization. In addition, our identifiable intangible assets include certain other subsidiary trade names, which are indefinite-lived and therefore not subject to amortization. Absent earlier indicators of impairment, we test for impairment of subsidiary trade names that are not subject to amortization on an annual basis (October 1). In performing this test, we calculate the fair value of each trade name using the “relief from royalty payments” methodology. This approach involves two steps: (a) estimating reasonable royalty rates for each trade name and (b) applying these royalty rates to a net revenue stream and discounting the resulting cash flows to determine fair value. This fair value is then compared with the carrying value of each trade name. If the carrying amount of the trade name is greater than the implied fair value of the trade name, an impairment in the amount of the excess is recognized and charged to operations. In addition, we review for impairment of identifiable intangible assets that are being amortized as well as other long-lived assets whenever facts and circumstances indicate that their carrying values may not be fully recoverable. This test compares their carrying values to the undiscounted pre-tax cash flows expected to result from the use of the assets. If the assets are impaired, the assets are written down to their fair values, generally determined based on their discounted estimated future cash flows. Given the negative market conditions disclosed above, we evaluated certain of our identifiable intangible assets and other long-lived assets for impairment during the second quarter of 2020. Such assets included those associated with the businesses in our United States industrial services segment. As a result of these assessments, during the quarter ended June 30, 2020, we recorded non-cash impairment charges of $7.3 million. We subsequently (as of October 1, 2020) performed our annual impairment assessment of all subsidiary trade names that are not subject to amortization and determined there was no incremental impairment of these assets. Additionally, we have not identified any impairment indicators during the three and six months ended June 30, 2021 that would necessitate an interim impairment assessment of either our identifiable intangible assets or other long-lived assets.