Business, Basis of Presentation and Significant Accounting Policies	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Business, Basis of Presentation and Significant Accounting Policies	Note 1 – Business, Basis of Presentation and Significant Accounting Policies Nature of the Business MasTec, Inc. (collectively with its subsidiaries, “MasTec” or the “Company”) is a leading infrastructure construction company operating mainly throughout North America across a range of industries. The Company’s primary activities include the engineering, building, installation, maintenance and upgrade of communications, energy, utility and other infrastructure, such as: wireless, wireline/fiber and customer fulfillment activities; petroleum and natural gas pipeline infrastructure; electrical utility transmission and distribution; power generation, including renewables; heavy civil; and industrial infrastructure. MasTec’s customers are primarily in these industries. MasTec reports its results under five reportable segments: (1) Communications; (2) Oil and Gas; (3) Electrical Transmission; (4) Power Generation and Industrial; and (5) Other. Basis of Presentation The accompanying condensed unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) for interim financial information and with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X. Pursuant to these rules and regulations, certain information and footnote disclosures normally included in the annual audited consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. The accompanying condensed consolidated balance sheet as of December 31, 2018 is derived from the Company’s audited financial statements as of that date. Because certain information and footnote disclosures have been condensed or omitted, these condensed unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto as of and for the year ended December 31, 2018 contained in the Company’s 2018 Annual Report on Form 10-K (the “2018 Form 10-K”). In management’s opinion, all normal and recurring adjustments considered necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented have been included. When necessary, certain prior year amounts have been reclassified to conform to the current period presentation. Interim period operating results do not necessarily indicate the results that may be expected for any other interim period or for the full fiscal year. The Company believes that the disclosures made in these condensed unaudited consolidated financial statements are adequate to make the information not misleading. Principles of Consolidation The accompanying condensed unaudited consolidated financial statements include MasTec, Inc. and its subsidiaries and include the accounts of all majority owned subsidiaries over which the Company exercises control and, when applicable, entities in which the Company has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. Other parties’ interests in entities that MasTec consolidates are reported as non-controlling interests within equity. Net income or loss attributable to non-controlling interests is reported as a separate line item below net income or loss. The Company’s investments in entities for which the Company does not have a controlling interest, but for which it has the ability to exert significant influence, are accounted for using either the equity method of accounting or under the fair value option. For equity investees in which the Company has an undivided interest in the assets, liabilities and profits or losses of an unincorporated entity, but the Company does not exercise control over the entity, the Company consolidates its proportional interest in the accounts of the entity. Translation of Foreign Currencies The assets and liabilities of foreign subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars at period-end exchange rates, with resulting translation gains or losses included within other comprehensive income or loss. Revenue and expenses are translated into U.S. dollars at average rates of exchange during the applicable period. Substantially all of the Company’s foreign operations use their local currency as their functional currency. Currency gains or losses resulting from transactions executed in currencies other than the functional currency are included in other income or expense, net. In these condensed unaudited consolidated financial statements, “$” means U.S. dollars unless otherwise noted. Management Estimates The preparation of consolidated financial statements in accordance with U.S. GAAP requires the use of estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates are based on historical experience and various other assumptions, the results of which form the basis of making judgments about the Company’s operating results and the carrying values of assets and liabilities that are not readily apparent from other sources. Key estimates include: the recognition of revenue and project profit or loss, which the Company defines as project revenue, less project costs of revenue, including project-related depreciation, in particular, on construction contracts accounted for under the cost-to-cost method, for which the recorded amounts require estimates of costs to complete and the amount of variable consideration included in the contract transaction price; allowances for doubtful accounts; fair value estimates, including those related to acquisitions, valuations of goodwill and intangible assets, acquisition-related contingent consideration and equity investments; asset lives used in computing depreciation and amortization; fair values of financial instruments; self-insurance liabilities; other accruals and allowances; income taxes; and the estimated effects of litigation and other contingencies. While management believes that such estimates are reasonable when considered in conjunction with the Company’s consolidated financial position and results of operations taken as a whole, actual results could differ materially from those estimates. Significant Accounting Policies Revenue Recognition The Company recognizes revenue from contracts with customers under Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”). Under Topic 606, revenue is recognized when, or as, control of promised goods and services is transferred to customers, and the amount of revenue recognized reflects the consideration to which an entity expects to be entitled in exchange for the goods and services transferred. Revenue is primarily recognized by the Company over time utilizing the cost-to-cost measure of progress, which best depicts the continuous transfer of control of goods or services to the customer, and correspondingly, when performance obligations are satisfied for the related contracts. Contracts. The Company derives revenue primarily from construction projects performed under: (i) master and other service agreements, which provide a menu of available services in a specific geographic territory that are utilized on an as-needed basis, and are typically priced using time and materials or a fixed price per unit basis; or (ii) contracts for specific projects requiring the construction and installation of an entire infrastructure system or specified units within an infrastructure system, which are subject to multiple pricing options, including fixed price, unit price, time and materials, or cost plus a markup. Revenue derived from projects performed under master service and other service agreements totaled 41% of consolidated revenue for both the three month periods ended March 31, 2019 and 2018. For certain master service and other service agreements under which the Company performs installation and maintenance services, primarily for install-to-the-home service providers in its Communications segment, revenue is recognized at a point in time. This is generally when the work order has been fulfilled, which is typically the same day the work is initiated. Point in time revenue accounted for approximately 6% and 9% of consolidated revenue for the three month periods ended March 31, 2019 and 2018, respectively. Substantially all of the Company’s other revenue is recognized over time. The cost estimation process for recognizing revenue over time under the cost-to-cost method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of total contract transaction price and total project costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected variable consideration are factors that influence estimates of the total contract transaction price, total costs to complete those contracts and the Company’s profit recognition. Changes in these factors could result in revisions to revenue in the period in which the revisions are determined, which could materially affect the Company’s consolidated results of operations for that period. Provisions for losses on uncompleted contracts are recorded in the period in which such losses are determined. For both the three month periods ended March 31, 2019 and 2018, project profit was affected by less than 5% as a result of changes in contract estimates included in projects that were in process as of December 31, 2018 and 2017. Revenue recognized for the three month periods ended March 31, 2019 and 2018 as a result of changes in revenue estimates, including from variable consideration, from performance obligations satisfied or partially satisfied in prior periods totaled approximately $12.5 million and $44.3 million, respectively. The Company may incur certain costs that can be capitalized, such as initial set-up or mobilization costs. Such costs, which are amortized over the life of the respective project, were not material for the three month periods ended March 31, 2019 and 2018. Performance Obligations. A performance obligation is a contractual promise to transfer a distinct good or service to a customer, and is the unit of account under Topic 606. The transaction price of a contract is allocated to each distinct performance obligation and recognized as revenue when or as the performance obligation is satisfied. The vast majority of the Company’s performance obligations are completed within one year. Remaining performance obligations represent the amount of unearned transaction price under contracts for which work is wholly or partially unperformed, including the Company’s share of unearned transaction price from its proportionately consolidated non-controlled joint ventures. As of March 31, 2019, the amount of the Company’s remaining performance obligations was $5.6 billion. The Company expects to recognize approximately $4.4 billion of its remaining performance obligations as revenue during 2019, with the remainder to be recognized primarily in 2020. Variable Consideration. Transaction prices for the Company’s contracts may include variable consideration, which comprises items such as change orders, claims and incentives. Management estimates variable consideration for a performance obligation utilizing estimation methods that it believes best predict the amount of consideration to which the Company will be entitled. Management’s estimates of variable consideration and the determination of whether to include estimated amounts in the transaction price are based largely on engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer and all other relevant information that is reasonably available at the time of the estimate. To the extent unapproved change orders, claims and other variable consideration reflected in transaction prices are not resolved in the Company’s favor, or to the extent incentives reflected in transaction prices are not earned, there could be reductions in, or reversals of, previously recognized revenue. As of March 31, 2019 and December 31, 2018, the Company included approximately $38 million and $56 million, respectively, of change orders and/or claims in the transaction price for certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These transaction price adjustments are included within costs and earnings in excess of billings or accounts receivable, net of allowance, as appropriate. As of both March 31, 2019 and December 31, 2018, these change orders and/or claims were primarily related to certain pipeline construction projects in the Oil and Gas segment. The Company actively engages with its customers to complete the final approval process, and generally expects these processes to be completed within one year. Amounts ultimately realized upon final acceptance by customers could be higher or lower than such estimated amounts. Recently Issued Accounting Pronouncements See the recent accounting pronouncements discussion below for information pertaining to the effects of recently adopted and other recent accounting pronouncements, as updated from the discussion in the Company’s 2018 Form 10-K. Accounting Pronouncements Adopted in 2019 Leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, Leases (Topic 842), which, together with its related clarifying ASUs (collectively, “ASU 2016-02”), provides revised guidance for lease accounting and related disclosure requirements, including a requirement for lessees to recognize right-of-use assets and lease liabilities on the balance sheet for leases with durations greater than twelve months. Under the new guidance, lessees classify leases as either finance or operating leases. Lease expense is recognized based on an effective interest method for finance leases, and on a straight-line basis over the term of the lease for operating leases. The Company adopted ASU 2016-02 during the first quarter of 2019 using the modified retrospective method as of January 1, 2019, without adjusting comparative periods in the financial statements. The most significant effect of the new guidance was the recognition of operating lease right-of-use assets and a liability for operating leases. The accounting for finance leases (capital leases) was substantially unchanged. The Company elected to utilize the package of practical expedients that allowed entities to: (1) not reassess whether any expired or existing contracts were or contained leases; (2) retain the existing classification of lease contracts as of the date of adoption; (3) not reassess initial direct costs for any existing leases; and (4) not separate non-lease components for all classes of leased assets. As of March 31, 2019, incremental lease assets and liabilities for operating leases totaled $223 million and $227 million, respectively, which amounts approximated the balances recognized at adoption. The adoption of Topic 842 did not have a material effect on the Company's results of operations or cash flows. For additional information about the Company’s leases, see Note 8 - Lease Obligations. Reclassification of Tax Effects from Other Comprehensive Income. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”). ASU 2018-02, which the Company adopted during the first quarter of 2019, permitted entities to reclassify the tax effects related to the change in the federal tax rate as a result of the 2017 Tax Act from accumulated other comprehensive income to retained earnings. The Company elected not to reclassify these tax effects, therefore, this ASU had no effect on its consolidated financial statements.

Note 1 – Business, Basis of Presentation and Significant Accounting Policies

Nature of the Business

MasTec, Inc. (collectively with its subsidiaries, “MasTec” or the “Company”) is a leading infrastructure construction company operating mainly throughout North America across a range of industries. The Company’s primary activities include the engineering, building, installation, maintenance and upgrade of communications, energy, utility and other infrastructure, such as: wireless, wireline/fiber and customer fulfillment activities; petroleum and natural gas pipeline infrastructure; electrical utility transmission and distribution; power generation, including renewables; heavy civil; and industrial infrastructure. MasTec’s customers are primarily in these industries. MasTec reports its results under five reportable segments: (1) Communications; (2) Oil and Gas; (3) Electrical Transmission; (4) Power Generation and Industrial; and (5) Other.

Basis of Presentation

The accompanying condensed unaudited consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) for interim financial information and with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X. Pursuant to these rules and regulations, certain information and footnote disclosures normally included in the annual audited consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. The accompanying condensed consolidated balance sheet as of December 31, 2018 is derived from the Company’s audited financial statements as of that date. Because certain information and footnote disclosures have been condensed or omitted, these condensed unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto as of and for the year ended December 31, 2018 contained in the Company’s 2018 Annual Report on Form 10-K (the “2018 Form 10-K”). In management’s opinion, all normal and recurring adjustments considered necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented have been included. When necessary, certain prior year amounts have been reclassified to conform to the current period presentation. Interim period operating results do not necessarily indicate the results that may be expected for any other interim period or for the full fiscal year. The Company believes that the disclosures made in these condensed unaudited consolidated financial statements are adequate to make the information not misleading.

Principles of Consolidation

The accompanying condensed unaudited consolidated financial statements include MasTec, Inc. and its subsidiaries and include the accounts of all majority owned subsidiaries over which the Company exercises control and, when applicable, entities in which the Company has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. Other parties’ interests in entities that MasTec consolidates are reported as non-controlling interests within equity. Net income or loss attributable to non-controlling interests is reported as a separate line item below net income or loss. The Company’s investments in entities for which the Company does not have a controlling interest, but for which it has the ability to exert significant influence, are accounted for using either the equity method of accounting or under the fair value option. For equity investees in which the Company has an undivided interest in the assets, liabilities and profits or losses of an unincorporated entity, but the Company does not exercise control over the entity, the Company consolidates its proportional interest in the accounts of the entity.

Translation of Foreign Currencies

The assets and liabilities of foreign subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars at period-end exchange rates, with resulting translation gains or losses included within other comprehensive income or loss. Revenue and expenses are translated into U.S. dollars at average rates of exchange during the applicable period. Substantially all of the Company’s foreign operations use their local currency as their functional currency. Currency gains or losses resulting from transactions executed in currencies other than the functional currency are included in other income or expense, net. In these condensed unaudited consolidated financial statements, “$” means U.S. dollars unless otherwise noted.

Management Estimates

The preparation of consolidated financial statements in accordance with U.S. GAAP requires the use of estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates are based on historical experience and various other assumptions, the results of which form the basis of making judgments about the Company’s operating results and the carrying values of assets and liabilities that are not readily apparent from other sources. Key estimates include: the recognition of revenue and project profit or loss, which the Company defines as project revenue, less project costs of revenue, including project-related depreciation, in particular, on construction contracts accounted for under the cost-to-cost method, for which the recorded amounts require estimates of costs to complete and the amount of variable consideration included in the contract transaction price; allowances for doubtful accounts; fair value estimates, including those related to acquisitions, valuations of goodwill and intangible assets, acquisition-related contingent consideration and equity investments; asset lives used in computing depreciation and amortization; fair values of financial instruments; self-insurance liabilities; other accruals and allowances; income taxes; and the estimated effects of litigation and other contingencies. While management believes that such estimates are reasonable when considered in conjunction with the Company’s consolidated financial position and results of operations taken as a whole, actual results could differ materially from those estimates.

Significant Accounting Policies

Revenue Recognition

The Company recognizes revenue from contracts with customers under Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”). Under Topic 606, revenue is recognized when, or as, control of promised goods and services is transferred to customers, and the amount of revenue recognized reflects the consideration to which an entity expects to be entitled in exchange for the goods and services transferred. Revenue is primarily recognized by the Company over time utilizing the cost-to-cost measure of progress, which best depicts the continuous transfer of control of goods or services to the customer, and correspondingly, when performance obligations are satisfied for the related contracts.

Contracts. The Company derives revenue primarily from construction projects performed under: (i) master and other service agreements, which provide a menu of available services in a specific geographic territory that are utilized on an as-needed basis, and are typically priced using time and materials or a fixed price per unit basis; or (ii) contracts for specific projects requiring the construction and installation of an entire infrastructure system or specified units within an infrastructure system, which are subject to multiple pricing options, including fixed price, unit price, time and materials, or cost plus a markup. Revenue derived from projects performed under master service and other service agreements totaled 41% of consolidated revenue for both the three month periods ended March 31, 2019 and 2018.

For certain master service and other service agreements under which the Company performs installation and maintenance services, primarily for install-to-the-home service providers in its Communications segment, revenue is recognized at a point in time. This is generally when the work order has been fulfilled, which is typically the same day the work is initiated. Point in time revenue accounted for approximately 6% and 9% of consolidated revenue for the three month periods ended March 31, 2019 and 2018, respectively. Substantially all of the Company’s other revenue is recognized over time.

The cost estimation process for recognizing revenue over time under the cost-to-cost method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of total contract transaction price and total project costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected variable consideration are factors that influence estimates of the total contract transaction price, total costs to complete those contracts and the Company’s profit recognition. Changes in these factors could result in revisions to revenue in the period in which the revisions are determined, which could materially affect the Company’s consolidated results of operations for that period. Provisions for losses on uncompleted contracts are recorded in the period in which such losses are determined. For both the three month periods ended March 31, 2019 and 2018, project profit was affected by less than 5% as a result of changes in contract estimates included in projects that were in process as of December 31, 2018 and 2017. Revenue recognized for the three month periods ended March 31, 2019 and 2018 as a result of changes in revenue estimates, including from variable consideration, from performance obligations satisfied or partially satisfied in prior periods totaled approximately $12.5 million and $44.3 million, respectively.

The Company may incur certain costs that can be capitalized, such as initial set-up or mobilization costs. Such costs, which are amortized over the life of the respective project, were not material for the three month periods ended March 31, 2019 and 2018.

Performance Obligations. A performance obligation is a contractual promise to transfer a distinct good or service to a customer, and is the unit of account under Topic 606. The transaction price of a contract is allocated to each distinct performance obligation and recognized as revenue when or as the performance obligation is satisfied. The vast majority of the Company’s performance obligations are completed within one year.

Remaining performance obligations represent the amount of unearned transaction price under contracts for which work is wholly or partially unperformed, including the Company’s share of unearned transaction price from its proportionately consolidated non-controlled joint ventures. As of March 31, 2019, the amount of the Company’s remaining performance obligations was $5.6 billion. The Company expects to recognize approximately $4.4 billion of its remaining performance obligations as revenue during 2019, with the remainder to be recognized primarily in 2020.

Variable Consideration. Transaction prices for the Company’s contracts may include variable consideration, which comprises items such as change orders, claims and incentives. Management estimates variable consideration for a performance obligation utilizing estimation methods that it believes best predict the amount of consideration to which the Company will be entitled. Management’s estimates of variable consideration and the determination of whether to include estimated amounts in the transaction price are based largely on engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer and all other relevant information that is reasonably available at the time of the estimate. To the extent unapproved change orders, claims and other variable consideration reflected in transaction prices are not resolved in the Company’s favor, or to the extent incentives reflected in transaction prices are not earned, there could be reductions in, or reversals of, previously recognized revenue.

As of March 31, 2019 and December 31, 2018, the Company included approximately $38 million and $56 million, respectively, of change orders and/or claims in the transaction price for certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These transaction price adjustments are included within costs and earnings in excess of billings or accounts receivable, net of allowance, as appropriate. As of both March 31, 2019 and December 31, 2018, these change orders and/or claims were primarily related to certain pipeline construction projects in the Oil and Gas segment. The Company actively engages with its customers to complete the final approval process, and generally expects these processes to be completed within one year. Amounts ultimately realized upon final acceptance by customers could be higher or lower than such estimated amounts.

Recently Issued Accounting Pronouncements

See the recent accounting pronouncements discussion below for information pertaining to the effects of recently adopted and other recent accounting pronouncements, as updated from the discussion in the Company’s 2018 Form 10-K.

Accounting Pronouncements Adopted in 2019

Leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, Leases (Topic 842), which, together with its related clarifying ASUs (collectively, “ASU 2016-02”), provides revised guidance for lease accounting and related disclosure requirements, including a requirement for lessees to recognize right-of-use assets and lease liabilities on the balance sheet for leases with durations greater than twelve months. Under the new guidance, lessees classify leases as either finance or operating leases. Lease expense is recognized based on an effective interest method for finance leases, and on a straight-line basis over the term of the lease for operating leases.

The Company adopted ASU 2016-02 during the first quarter of 2019 using the modified retrospective method as of January 1, 2019, without adjusting comparative periods in the financial statements. The most significant effect of the new guidance was the recognition of operating lease right-of-use assets and a liability for operating leases. The accounting for finance leases (capital leases) was substantially unchanged. The Company elected to utilize the package of practical expedients that allowed entities to: (1) not reassess whether any expired or existing contracts were or contained leases; (2) retain the existing classification of lease contracts as of the date of adoption; (3) not reassess initial direct costs for any existing leases; and (4) not separate non-lease components for all classes of leased assets.

As of March 31, 2019, incremental lease assets and liabilities for operating leases totaled $223 million and $227 million, respectively, which amounts approximated the balances recognized at adoption. The adoption of Topic 842 did not have a material effect on the Company's results of operations or cash flows. For additional information about the Company’s leases, see Note 8 - Lease Obligations.

Reclassification of Tax Effects from Other Comprehensive Income. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”). ASU 2018-02, which the Company adopted during the first quarter of 2019, permitted entities to reclassify the tax effects related to the change in the federal tax rate as a result of the 2017 Tax Act from accumulated other comprehensive income to retained earnings. The Company elected not to reclassify these tax effects, therefore, this ASU had no effect on its consolidated financial statements.