Summary of Significant Accounting Policies (Notes)	12 Months Ended
Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation The consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries and joint ventures. Significant intercompany accounts and transactions have been eliminated. All investments over which we exercise significant influence, but do not control (a 20% to 50% ownership interest), are accounted for using the equity method of accounting. For joint ventures that have been accounted for using the consolidation method of accounting, noncontrolling interests represent the allocation of earnings to our joint venture partners who either have a minority-ownership interest in the joint venture or are not at risk for the majority of losses of the joint venture. The results of operations of companies acquired have been included in the results of operations from the date of the respective acquisition. Principles of Preparation The preparation of the consolidated financial statements, in conformity with accounting principles generally accepted in the United States, requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates. Our reportable segments reflect certain reclassifications of prior year amounts from our United States mechanical construction and facilities services segment to our United States building services and our United States industrial services segments due to changes in our internal reporting structure. During the third quarter of 2014, we ceased construction operations in the United Kingdom. The results of the construction operations of our United Kingdom segment for all periods are presented as discontinued operations. Revenue Recognition The Company adopted Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“ASC 606”) on January 1, 2018. In accordance with ASC 606, revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. Refer to Note 3 - Revenue from Contracts with Customers of the notes to consolidated financial statements for additional information. For the periods presented prior to the adoption of ASC 606, revenues from long-term construction contracts were recognized in accordance with ASC Topic 605-35, “Revenue Recognition-Construction-Type and Production-Type Contracts.” Revenues from the performance of services for maintenance, repair and retrofit work were recognized consistent with the performance of the services, generally on a pro-rata basis over the life of the contractual arrangement. Revenues related to the engineering, manufacturing and repairing of shell and tube heat exchangers were recognized when the product was shipped and all other revenue recognition criteria were met. Cash and cash equivalents For purposes of the consolidated financial statements, we consider all highly liquid instruments with original maturities of three months or less to be cash equivalents. We maintain a centralized cash management system whereby our excess cash balances are invested in high quality, short-term money market instruments, which are considered cash equivalents. We have cash balances in certain of our domestic bank accounts that exceed federally insured limits. Allowance for Doubtful Accounts Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company maintains an allowance for doubtful accounts. This allowance is based upon the best estimate of the probable losses in existing accounts receivable. The Company determines the allowances based upon individual accounts when information indicates the customers may have an inability to meet their financial obligations, as well as historical collection and write-off experience. These amounts are re-evaluated and adjusted on a regular basis as additional information is received. Actual write-offs are charged against the allowance when collection efforts have been unsuccessful. At December 31, 2019 and 2018, our accounts receivable of $2,030.8 million and $1,773.6 million, respectively, were recorded net of allowances for doubtful accounts of $14.5 million and $15.4 million, respectively. The provision for doubtful accounts during 2019, 2018, and 2017 amounted to approximately $2.6 million, $2.1 million, and $7.3 million, respectively. Inventories Inventories are stated at the lower of cost or net realizable value. Cost is determined principally using the average cost method. Property, plant and equipment Property, plant and equipment is stated at cost. Depreciation, including amortization of assets under finance leases, is recorded principally using the straight-line method over estimated useful lives of 3 to 10 years for machinery and equipment, 3 to 7 years for vehicles, furniture and fixtures and computer hardware/software, and 25 years for buildings. Leasehold improvements are amortized over the shorter of the remaining life of the lease term or the expected useful life of the improvement. The carrying values of property, plant and equipment are reviewed for impairment whenever facts and circumstances indicate that the carrying amount may not be fully recoverable. In performing this review for recoverability, property, plant and equipment is assessed for possible impairment by comparing their carrying values to their undiscounted net pre-tax cash flows expected to result from the use of the asset. Impaired assets are written down to their fair values, generally determined based on their estimated future discounted cash flows. Based on the results of our testing for the years ended December 31, 2019, 2018, and 2017, no impairment of property, plant and equipment was recognized. Goodwill and Identifiable Intangible Assets Goodwill and other identifiable intangible assets with indefinite lives that are not being amortized, such as trade names, are tested at least annually for impairment (which we test each October 1, absent any earlier identified impairment indicators) and are written down if impaired. Identifiable intangible assets with finite lives are amortized over their useful lives and are reviewed for impairment whenever facts and circumstances indicate that their carrying values may not be fully recoverable. See Note 9 - Goodwill and Identifiable Intangible Assets of the notes to consolidated financial statements for additional information. Insurance Liabilities Insurance liabilities for automobile liability, workers’ compensation and general liability claims are determined actuarially based on claims filed and an estimate of claims incurred but not yet reported. At December 31, 2019 and 2018, the estimated current portion of such undiscounted insurance liabilities of $48.3 million and $44.6 million, respectively, were included in “Other accrued expenses and liabilities” in the accompanying Consolidated Balance Sheets. The estimated non-current portion of such undiscounted insurance liabilities included in “Other long-term obligations” at December 31, 2019 and 2018 were $186.0 million and $179.1 million, respectively. The current portion of anticipated insurance recoveries of $13.8 million and $12.6 million at December 31, 2019 and 2018, respectively, were included in “Prepaid expenses and other” and the non-current portion of anticipated insurance recoveries of $50.9 million and $49.3 million at December 31, 2019 and 2018, respectively, were included in “Other assets” in the accompanying Consolidated Balance Sheets. Foreign Operations The financial statements and transactions of our foreign subsidiaries are maintained in their functional currency and translated into U.S. dollars in accordance with Accounting Standards Codification Topic 830, “Foreign Currency Matters.” Translation adjustments have been recorded as “Accumulated other comprehensive loss,” a separate component of “Equity.” Income Taxes We account for income taxes in accordance with the provisions of Accounting Standards Codification Topic 740, “Income Taxes” (“ASC 740”). ASC 740 requires an asset and liability approach which requires the recognition of deferred income tax assets and deferred income tax liabilities for the expected future tax consequences of temporary differences between the carrying amounts and the tax bases of assets and liabilities. Valuation allowances are established when necessary to reduce deferred income tax assets when it is more likely than not that a tax benefit will not be realized. We account for uncertain tax positions in accordance with the provisions of ASC 740. We recognize accruals of interest related to unrecognized tax benefits as a component of the income tax provision. Valuation of Share-Based Compensation Plans We have various types of share-based compensation plans and programs, which are administered by our Board of Directors or its Compensation and Personnel Committee. See Note 14 - Share-Based Compensation Plans of the notes to consolidated financial statements for additional information regarding the share-based compensation plans and programs. We account for share-based payments in accordance with the provisions of Accounting Standards Codification Topic 718, “Compensation-Stock Compensation” (“ASC 718”). ASC 718 requires that all share-based payments issued to acquire goods or services, including grants of employee stock options, be recognized in the statement of operations based on their fair values. Compensation expense related to share-based awards is recognized over the requisite service period, which is generally the vesting period. For shares subject to graded vesting, our policy is to apply the straight-line method in recognizing compensation expense. ASC 718 requires the benefits of tax deductions in excess of recognized compensation expense to be recognized in the Consolidated Statements of Operations when the underlying awards vest or are settled. New Accounting Pronouncements On January 1, 2019, we adopted the accounting pronouncement issued by the Financial Accounting Standards Board (“FASB”) to replace existing lease accounting guidance. This pronouncement is intended to provide enhanced transparency and comparability by requiring lessees to record right-of-use assets and corresponding lease liabilities on the balance sheet for most leases. Expenses associated with leases continue to be recognized in a manner similar to previous accounting guidance. We adopted this pronouncement utilizing the transition practical expedient added by the FASB, which eliminated the requirement that entities apply the new lease standard to the comparative periods presented in the year of adoption. The adoption of this accounting pronouncement resulted in the recognition of operating lease right-of-use assets and associated lease liabilities on our balance sheet of $220.2 million and $227.1 million, respectively, as of January 1, 2019. Additional required disclosures have been included within Note 17 - Leases of the notes to consolidated financial statements. Such adoption did not have an impact on our liquidity, results of operations or our compliance with the various covenants contained within our 2016 Credit Agreement as described in further detail within Note 10 - Debt of the notes to consolidated financial statements. On January 1, 2019, we adopted the accounting pronouncement issued by the FASB related to the reporting of certain items in accumulated other comprehensive income (loss) (“AOCI”). This guidance provides entities the option to reclassify to retained earnings certain tax effects stranded in AOCI as a result of tax reform. As part of our adoption of this accounting pronouncement, we elected not to reclassify the stranded tax effects related to the retirement plans of our United States subsidiaries as such amounts are immaterial. Tax effects remaining in AOCI will be released upon liquidation of each individual retirement plan. In June 2016, an accounting pronouncement was issued by the FASB which changes the way in which entities estimate and present credit losses for most financial assets, including accounts receivable. This pronouncement is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. In preparation for adoption, we have substantially completed a process to identify and group financial assets with similar characteristics into collective pools. We have additionally begun implementing processes and internal controls to identify information, including macroeconomic forecasts and key credit indicators, relevant to estimating expected credit losses. As a result of the procedures performed to date, we do not anticipate that the adoption of this pronouncement will have a material impact on our financial position and/or results of operations.

The consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries and joint ventures. Significant intercompany accounts and transactions have been eliminated. All investments over which we exercise significant influence, but do not control (a 20% to 50% ownership interest), are accounted for using the equity method of accounting. For joint ventures that have been accounted for using the consolidation method of accounting, noncontrolling interests represent the allocation of earnings to our joint venture partners who either have a minority-ownership interest in the joint venture or are not at risk for the majority of losses of the joint venture.

The preparation of the consolidated financial statements, in conformity with accounting principles generally accepted in the United States, requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates.

Our reportable segments reflect certain reclassifications of prior year amounts from our United States mechanical construction and facilities services segment to our United States building services and our United States industrial services segments due to changes in our internal reporting structure.

The Company adopted Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“ASC 606”) on January 1, 2018. In accordance with ASC 606, revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. Refer to Note 3 - Revenue from Contracts with Customers of the notes to consolidated financial statements for additional information.

For the periods presented prior to the adoption of ASC 606, revenues from long-term construction contracts were recognized in accordance with ASC Topic 605-35, “Revenue Recognition-Construction-Type and Production-Type Contracts.” Revenues from the performance of services for maintenance, repair and retrofit work were recognized consistent with the performance of the services, generally on a pro-rata basis over the life of the contractual arrangement. Revenues related to the engineering, manufacturing and repairing of shell and tube heat exchangers were recognized when the product was shipped and all other revenue recognition criteria were met.

For purposes of the consolidated financial statements, we consider all highly liquid instruments with original maturities of three months or less to be cash equivalents. We maintain a centralized cash management system whereby our excess cash balances are invested in high quality, short-term money market instruments, which are considered cash equivalents. We have cash balances in certain of our domestic bank accounts that exceed federally insured limits.

Accounts receivable are recorded at the invoiced amount and do not bear interest. The Company maintains an allowance for doubtful accounts. This allowance is based upon the best estimate of the probable losses in existing accounts receivable. The Company determines the allowances based upon individual accounts when information indicates the customers may have an inability to meet their financial obligations, as well as historical collection and write-off experience. These amounts are re-evaluated and adjusted on a regular basis as additional information is received. Actual write-offs are charged against the allowance when collection efforts have been unsuccessful. At December 31, 2019 and 2018, our accounts receivable of $2,030.8 million and $1,773.6 million, respectively, were recorded net of allowances for doubtful accounts of $14.5 million and $15.4 million, respectively. The provision for doubtful accounts during 2019, 2018, and 2017 amounted to approximately $2.6 million, $2.1 million, and $7.3 million, respectively.

Property, plant and equipment is stated at cost. Depreciation, including amortization of assets under finance leases, is recorded principally using the straight-line method over estimated useful lives of 3 to 10 years for machinery and equipment, 3 to 7 years for vehicles, furniture and fixtures and computer hardware/software, and 25 years for buildings. Leasehold improvements are amortized over the shorter of the remaining life of the lease term or the expected useful life of the improvement.

The carrying values of property, plant and equipment are reviewed for impairment whenever facts and circumstances indicate that the carrying amount may not be fully recoverable. In performing this review for recoverability, property, plant and equipment is assessed for possible impairment by comparing their carrying values to their undiscounted net pre-tax cash flows expected to result from the use of the asset. Impaired assets are written down to their fair values, generally determined based on their estimated future discounted cash flows. Based on the results of our testing for the years ended December 31, 2019, 2018, and 2017, no impairment of property, plant and equipment was recognized.

Goodwill and other identifiable intangible assets with indefinite lives that are not being amortized, such as trade names, are tested at least annually for impairment (which we test each October 1, absent any earlier identified impairment indicators) and are written down if impaired. Identifiable intangible assets with finite lives are amortized over their useful lives and are reviewed for impairment whenever facts and circumstances indicate that their carrying values may not be fully recoverable. See Note 9 - Goodwill and Identifiable Intangible Assets of the notes to consolidated financial statements for additional information.

Insurance liabilities for automobile liability, workers’ compensation and general liability claims are determined actuarially based on claims filed and an estimate of claims incurred but not yet reported. At December 31, 2019 and 2018, the estimated current portion of such undiscounted insurance liabilities of $48.3 million and $44.6 million, respectively, were included in “Other accrued expenses and liabilities” in the accompanying Consolidated Balance Sheets. The estimated non-current portion of such undiscounted insurance liabilities included in “Other long-term obligations” at December 31, 2019 and 2018 were $186.0 million and $179.1 million, respectively. The current portion of anticipated insurance recoveries of $13.8 million and $12.6 million at December 31, 2019 and 2018, respectively, were included in “Prepaid expenses and other” and the non-current portion of anticipated insurance recoveries of $50.9 million and $49.3 million at December 31, 2019 and 2018, respectively, were included in “Other assets” in the accompanying Consolidated Balance Sheets.

The financial statements and transactions of our foreign subsidiaries are maintained in their functional currency and translated into U.S. dollars in accordance with Accounting Standards Codification Topic 830, “Foreign Currency Matters.” Translation adjustments have been recorded as “Accumulated other comprehensive loss,” a separate component of “Equity.”

We account for income taxes in accordance with the provisions of Accounting Standards Codification Topic 740, “Income Taxes” (“ASC 740”). ASC 740 requires an asset and liability approach which requires the recognition of deferred income tax assets and deferred income tax liabilities for the expected future tax consequences of temporary differences between the carrying amounts and the tax bases of assets and liabilities. Valuation allowances are established when necessary to reduce deferred income tax assets when it is more likely than not that a tax benefit will not be realized.

We have various types of share-based compensation plans and programs, which are administered by our Board of Directors or its Compensation and Personnel Committee. See Note 14 - Share-Based Compensation Plans of the notes to consolidated financial statements for additional information regarding the share-based compensation plans and programs.

We account for share-based payments in accordance with the provisions of Accounting Standards Codification Topic 718, “Compensation-Stock Compensation” (“ASC 718”). ASC 718 requires that all share-based payments issued to acquire goods or services, including grants of employee stock options, be recognized in the statement of operations based on their fair values. Compensation expense related to share-based awards is recognized over the requisite service period, which is generally the vesting period. For shares subject to graded vesting, our policy is to apply the straight-line method in recognizing compensation expense. ASC 718 requires the benefits of tax deductions in excess of recognized compensation expense to be recognized in the Consolidated Statements of Operations when the underlying awards vest or are settled.

On January 1, 2019, we adopted the accounting pronouncement issued by the Financial Accounting Standards Board (“FASB”) to replace existing lease accounting guidance. This pronouncement is intended to provide enhanced transparency and comparability by requiring lessees to record right-of-use assets and corresponding lease liabilities on the balance sheet for most leases. Expenses associated with leases continue to be recognized in a manner similar to previous accounting guidance. We adopted this pronouncement utilizing the transition practical expedient added by the FASB, which eliminated the requirement that entities apply the new lease standard to the comparative periods presented in the year of adoption. The adoption of this accounting pronouncement resulted in the recognition of operating lease right-of-use assets and associated lease liabilities on our balance sheet of $220.2 million and $227.1 million, respectively, as of January 1, 2019. Additional required disclosures have been included within Note 17 - Leases of the notes to consolidated financial statements. Such adoption did not have an impact on our liquidity, results of operations or our compliance with the various covenants contained within our 2016 Credit Agreement as described in further detail within Note 10 - Debt of the notes to consolidated financial statements.

On January 1, 2019, we adopted the accounting pronouncement issued by the FASB related to the reporting of certain items in accumulated other comprehensive income (loss) (“AOCI”). This guidance provides entities the option to reclassify to retained earnings certain tax effects stranded in AOCI as a result of tax reform. As part of our adoption of this accounting pronouncement, we elected not to reclassify the stranded tax effects related to the retirement plans of our United States subsidiaries as such amounts are immaterial. Tax effects remaining in AOCI will be released upon liquidation of each individual retirement plan.

In June 2016, an accounting pronouncement was issued by the FASB which changes the way in which entities estimate and present credit losses for most financial assets, including accounts receivable. This pronouncement is effective for annual and interim periods beginning after December 15, 2019, with early adoption permitted. In preparation for adoption, we have substantially completed a process to identify and group financial assets with similar characteristics into collective pools. We have additionally begun implementing processes and internal controls to identify information, including macroeconomic forecasts and key credit indicators, relevant to estimating expected credit losses. As a result of the procedures performed to date, we do not anticipate that the adoption of this pronouncement will have a material impact on our financial position and/or results of operations.