Summary of Significant Accounting Policies (Notes)	12 Months Ended
Dec. 31, 2018
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 segment 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, 2018 and 2017, our accounts receivable of $1,773.6 million and $1,607.9 million, respectively, were recorded net of allowances for doubtful accounts of $15.4 million and $17.2 million, respectively. The provision for doubtful accounts during 2018, 2017 and 2016 amounted to approximately $2.1 million, $7.3 million and $6.2 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 capital 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 service 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, 2018, 2017 and 2016, 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 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, 2018 and 2017, the estimated current portion of such undiscounted insurance liabilities of $44.6 million and $47.3 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, 2018 and 2017 were $179.1 million and $173.2 million, respectively. The current portion of anticipated insurance recoveries of $12.6 million and $14.9 million at December 31, 2018 and 2017, respectively, were included in “Prepaid expenses and other” and the non-current portion of anticipated insurance recoveries of $49.3 million and $48.6 million at December 31, 2018 and 2017, 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 ASC 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 ASC 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 ASC 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, 2018, we adopted the accounting pronouncement issued by the Financial Accounting Standards Board (“FASB”) to clarify existing guidance on revenue recognition. This guidance includes the required steps to achieve the core principle that a company should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. We adopted this pronouncement on a modified retrospective basis, and its impact on our financial position and results of operations, as well as required additional disclosures, are included in Note 3 - Revenue from Contracts with Customers. As a result of the adoption of this standard, certain changes have been made to the Consolidated Balance Sheets. The accounts previously named “Costs and estimated earnings in excess of billings on uncompleted contracts” and “Billings in excess of costs and estimated earnings on uncompleted contracts” have been renamed “Contract assets” and “Contract liabilities”, respectively. In addition, for periods beginning after December 31, 2017, amounts representing deferred revenues on services contracts, which were previously included in “Other accrued expenses and liabilities” within the Consolidated Balance Sheets, have been reclassified as “Contract liabilities.” On January 1, 2018, we adopted the accounting pronouncement issued by the FASB to clarify how entities should present restricted cash and restricted cash equivalents in the statement of cash flows. This guidance requires entities to show changes in the total of cash, cash equivalents and restricted cash in the statement of cash flows. This guidance was adopted on a retrospective basis, and such adoption did not have a material impact on our financial position and/or results of operations. During 2018, we adopted the accounting pronouncement issued by the FASB that modifies the presentation of net periodic pension and post retirement benefit costs within the statement of operations. This guidance requires the components of the net periodic pension and post retirement benefit costs, other than service costs, to be recognized below operating income. This change was applied on a retrospective basis, and such adoption did not have a material impact on our financial position and/or results of operations. In February 2016, an accounting pronouncement was issued by the 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 will continue to be recognized in a manner similar to current accounting guidance. This pronouncement is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. In preparation for adoption, we have performed a process to identify a complete population of our leases, including the review of various contracts to identify whether such arrangements convey the right to control the use of an identified asset. We have additionally implemented new accounting systems, processes, and controls and have drafted revised accounting policies to assist with the adoption of this pronouncement, including the enhanced disclosure requirements. We will adopt this pronouncement on January 1, 2019 utilizing the transition practical expedient added by the FASB which eliminates the requirement that entities apply the new lease standard to the comparative periods presented in the year of adoption. We will additionally utilize the package of practical expedients permitted under the new standard which, among other things, allows us to not reassess the lease classification for any existing leases. Further, as permitted by the standard, we will make an accounting policy election not to record right-of-use assets or lease liabilities for leases with an initial term of 12 months or less. Instead, consistent with current accounting guidance, we will recognize payments for such leases in the statement of operations on a straight-line basis over the lease term. Upon adoption on January 1, 2019, we estimate this accounting pronouncement will result in the recognition of additional assets and liabilities on our balance sheet of between $200.0 million and $225.0 million. We do not believe the new standard will have an impact on our liquidity or results of operations, and such adoption will not impact 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.

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 segment 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, 2018 and 2017, our accounts receivable of $1,773.6 million and $1,607.9 million, respectively, were recorded net of allowances for doubtful accounts of $15.4 million and $17.2 million, respectively. The provision for doubtful accounts during 2018, 2017 and 2016 amounted to approximately $2.1 million, $7.3 million and $6.2 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 capital 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 service 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, 2018, 2017 and 2016, 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 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, 2018 and 2017, the estimated current portion of such undiscounted insurance liabilities of $44.6 million and $47.3 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, 2018 and 2017 were $179.1 million and $173.2 million, respectively. The current portion of anticipated insurance recoveries of $12.6 million and $14.9 million at December 31, 2018 and 2017, respectively, were included in “Prepaid expenses and other” and the non-current portion of anticipated insurance recoveries of $49.3 million and $48.6 million at December 31, 2018 and 2017, 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 ASC 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 ASC 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 ASC 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, 2018, we adopted the accounting pronouncement issued by the Financial Accounting Standards Board (“FASB”) to clarify existing guidance on revenue recognition. This guidance includes the required steps to achieve the core principle that a company should recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. We adopted this pronouncement on a modified retrospective basis, and its impact on our financial position and results of operations, as well as required additional disclosures, are included in Note 3 - Revenue from Contracts with Customers. As a result of the adoption of this standard, certain changes have been made to the Consolidated Balance Sheets. The accounts previously named “Costs and estimated earnings in excess of billings on uncompleted contracts” and “Billings in excess of costs and estimated earnings on uncompleted contracts” have been renamed “Contract assets” and “Contract liabilities”, respectively. In addition, for periods beginning after December 31, 2017, amounts representing deferred revenues on services contracts, which were previously included in “Other accrued expenses and liabilities” within the Consolidated Balance Sheets, have been reclassified as “Contract liabilities.”

On January 1, 2018, we adopted the accounting pronouncement issued by the FASB to clarify how entities should present restricted cash and restricted cash equivalents in the statement of cash flows. This guidance requires entities to show changes in the total of cash, cash equivalents and restricted cash in the statement of cash flows. This guidance was adopted on a retrospective basis, and such adoption did not have a material impact on our financial position and/or results of operations.

During 2018, we adopted the accounting pronouncement issued by the FASB that modifies the presentation of net periodic pension and post retirement benefit costs within the statement of operations. This guidance requires the components of the net periodic pension and post retirement benefit costs, other than service costs, to be recognized below operating income. This change was applied on a retrospective basis, and such adoption did not have a material impact on our financial position and/or results of operations.

In February 2016, an accounting pronouncement was issued by the 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 will continue to be recognized in a manner similar to current accounting guidance. This pronouncement is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. In preparation for adoption, we have performed a process to identify a complete population of our leases, including the review of various contracts to identify whether such arrangements convey the right to control the use of an identified asset. We have additionally implemented new accounting systems, processes, and controls and have drafted revised accounting policies to assist with the adoption of this pronouncement, including the enhanced disclosure requirements. We will adopt this pronouncement on January 1, 2019 utilizing the transition practical expedient added by the FASB which eliminates the requirement that entities apply the new lease standard to the comparative periods presented in the year of adoption. We will additionally utilize the package of practical expedients permitted under the new standard which, among other things, allows us to not reassess the lease classification for any existing leases. Further, as permitted by the standard, we will make an accounting policy election not to record right-of-use assets or lease liabilities for leases with an initial term of 12 months or less. Instead, consistent with current accounting guidance, we will recognize payments for such leases in the statement of operations on a straight-line basis over the lease term. Upon adoption on January 1, 2019, we estimate this accounting pronouncement will result in the recognition of additional assets and liabilities on our balance sheet of between $200.0 million and $225.0 million. We do not believe the new standard will have an impact on our liquidity or results of operations, and such adoption will not impact 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.