Business, Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying 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.
Reclassifications	When necessary, certain prior year amounts have been reclassified to conform with the current period presentation.
Translation of Foreign Currencies	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.
Management Estimates	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.
Revenue Recognition	Revenue Recognition The Company adopted the requirements of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers, which is also referred to as Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”), under the modified retrospective transition approach effective January 1, 2018, with application to all existing contracts that were not substantially completed as of January 1, 2018. The difference between the recognition criteria under Topic 606 and the Company’s previous revenue recognition practices under the previous revenue recognition guidance, ASC Topic 605-35, was recognized through a cumulative effect adjustment of approximately $2 million that was made to the opening balance of retained earnings as of January 1, 2018. Consistent with the modified retrospective transition approach, the comparative 2017 prior period was not adjusted to conform to the current period presentation. 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. The adoption of Topic 606 did not have a material effect on the timing or amount of revenue recognized as compared with the Company’s previous revenue recognition practices. Revenue is primarily recognized by the Company over time utilizing the cost-to-cost measure of progress, which is an input method, on contracts for specific projects, and for certain master service and other service agreements, consistent with the Company’s previous revenue recognition practices. Under Topic 606, the cost-to-cost measure of progress best depicts the continuous transfer of control of goods or services to the customer, and correspondingly, when performance obligations are satisfied, for these 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 35%, 36% and 43% of consolidated revenue for the years ended December 31, 2018, 2017 and 2016, respectively. Fixed price contracts provide for a fixed amount of revenue for the entire project. Revenue from these contracts, as well as for certain projects pursuant to master and other service agreements, is recognized over time using the cost-to-cost measure of progress. For these contracts, the cost-to-cost measure of progress best depicts the continuous transfer of control of goods or services to the customer. Such contracts provide that the customer accept completion of progress to date and compensate the Company for services rendered. 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 7% of consolidated revenue for the year ended December 31, 2018. Substantially all of the Company’s other revenue is recognized over time. Contract costs include all direct materials, labor and subcontracted costs, as well as indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and the operational costs of capital equipment. 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 years ended December 31, 2018 and 2017, 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, 2017 and 2016. Revenue recognized for the year ended December 31, 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 $38.5 million. 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 year ended December 31, 2018. The timing of customer billings is generally dependent upon advance billing terms, milestone billings based on completion of certain phases of work, or when services are provided. Under the typical payment terms of master and other service agreements and fixed price contracts, the customer makes progress payments based on quantifiable measures of performance by the Company as defined by each specific agreement. Progress payments, generally net of amounts retained, are paid by the customer over the duration of the contract. For install-to-the-home contracts, work orders are billed and paid as completed. Amounts billed and due from customers, as well as the amount of contract assets, are classified within accounts receivable, net, in the consolidated balance sheets. See Note 5 - Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities for related discussion. Amounts expected to be collected beyond one year are classified as other long-term assets. 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 Company’s contracts often require significant services to integrate complex activities and equipment into a single deliverable, and are therefore generally accounted for as a single performance obligation, even when delivering multiple distinct services. Contract amendments and change orders, which are generally not distinct from the existing contract, are typically accounted for as a modification of the existing contract and performance obligation. The vast majority of the Company’s performance obligations are completed within one year. When more than one contract is entered into with a customer on or close to the same date, the Company evaluates whether those contracts should be combined and accounted for as a single contract, as well as whether those contracts should be accounted for as one, or more than one, performance obligation. This evaluation requires significant judgment and is based on the facts and circumstances of the various contracts. 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 December 31, 2018, the amount of the Company’s remaining performance obligations was $5.0 billion. The Company expects to recognize approximately $4.3 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. Variable consideration is included in the estimated transaction price if it is probable that when the uncertainty associated with the variable consideration is resolved, there will not be a significant reversal of the cumulative amount of revenue that has been recognized. 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. The effect of variable consideration on the transaction price of a performance obligation is typically recognized as an adjustment to revenue on a cumulative catch-up basis, as such variable consideration, which typically pertains to changed conditions and scope, is generally for services encompassed under the existing contract. 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 December 31, 2018 and 2017, the Company included approximately $56 million and $146 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 December 31, 2018 and 2017, 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.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Management analyzes the collectibility of trade accounts receivable and the adequacy of the allowance for doubtful accounts on a regular basis taking into consideration the aging of account balances, historical bad debt experience, customer concentrations, customer credit-worthiness, customer financial condition and credit reports, availability of mechanics’ and other liens, existence of payment bonds and other sources of payment and the current economic environment. The Company establishes an allowance for anticipated losses on its accounts receivable balances either when a business unit has historical experience of losses that are considered to be ordinary course, and/or for specific receivables, when it is probable that the receivable is not collectible and the loss can be reasonably estimated. Amounts are written off against the allowance when they are considered to be uncollectible. If estimates of the collectibility of accounts receivable change, or should customers experience unanticipated financial difficulties, or if anticipated recoveries in existing bankruptcies or other work-out situations fail to materialize, additional allowances may be required. Estimates of collectibility are subject to significant change during times of economic weakness or uncertainty in either the overall economy or within the industries served by MasTec. Management actively monitors the economic environment and its impact on MasTec’s customers in connection with its evaluation of the Company’s accounts receivable portfolio and the adequacy of its allowance for doubtful accounts.
Inventories	Inventories Inventories consist of materials and supplies for construction and installation projects, which are valued at the lower of cost or net realizable value using the average cost or specific identification methods of costing. For materials or supplies purchased on behalf of specific customers or projects, loss of the customer or cancellation of the project could result in an impairment of the value of materials purchased. The value of inventory may also decrease due to obsolescence, physical deterioration, damage, changes in price levels, or other causes. Inventory valuation allowances are determined based upon specific facts and circumstances and market conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. Highly liquid investments purchased with an original maturity of three months or less are carried at fair value. On a daily basis, available funds are swept from the Company’s depository accounts into a concentration account and used to repay outstanding revolving loans under the Company’s senior secured credit facility. Cash balances maintained by certain operating subsidiaries and by entities that are proportionately consolidated that are not swept into the concentration account, as well as deposits made subsequent to the daily cash sweep, are classified as cash. Included in the Company’s cash balances as of December 31, 2018 and 2017 are amounts held by entities that are proportionately consolidated totaling $11.8 million and $17.3 million, respectively. These amounts are available to support the operations of those entities, but are not available for the Company’s other operations. The Company generally does not fund its disbursement accounts for checks it has written until the checks are presented to the bank for payment. Outstanding checks that have not yet cleared through the banking system represent book overdrafts, which are classified within accounts payable. There are no compensating balance requirements associated with the Company’s depository accounts and there are no other restrictions on the transfer of cash associated with the Company’s depository accounts.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments include cash and cash equivalents, accounts and notes receivable, cash collateral deposited with insurance carriers, life insurance assets, equity investments, deferred compensation plan assets and liabilities, accounts payable and other current liabilities, acquisition-related contingent consideration and debt obligations. Fair value is the price that would be received to sell an asset or the amount paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value guidance establishes a valuation hierarchy, which requires maximizing the use of observable inputs when measuring fair value. The three levels of inputs that may be used are: (i) Level 1 - quoted market prices in active markets for identical assets or liabilities; (ii) Level 2 - observable market-based inputs or other observable inputs; and (iii) Level 3 - significant unobservable inputs that cannot be corroborated by observable market data, which are generally determined using valuation models incorporating management estimates of market participant assumptions. In instances in which the inputs used to measure fair value fall into different levels of the fair value hierarchy, the fair value measurement classification is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Management’s assessment of the significance of a particular item to the fair value measurement in its entirety requires judgment, including the consideration of inputs specific to the asset or liability. Fair values of financial instruments are estimated using public market prices, quotes from financial institutions and other available information. Due to their short-term maturity, the carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and other current liabilities approximate their fair values. Management believes the carrying values of notes and other receivables, cash collateral deposited with insurance carriers, and outstanding balances on its credit facilities approximate their fair values.
Variable Interest Entities	Management determines whether each business entity in which it has equity interests, debt, or other investments constitutes a variable interest entity (“VIE”) based on the nature and characteristics of such arrangements. If an investment arrangement is determined to be a VIE, then management determines if the Company is the VIE’s primary beneficiary by evaluating several factors, including the Company’s: (i) risks and responsibilities; (ii) ownership interests; (iii) decision making powers; and (iv) financial interests, among other factors. If management determines the Company is the primary beneficiary of a VIE, then it would be consolidated, and other parties’ interests in the VIE would be accounted for as non-controlling interests. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the primary activities of the VIE and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE, which, in either case, could be significant to the VIE. As of December 31, 2018, the Company determined that certain of its investment arrangements were VIEs. The Company does not, however, have the power to direct the primary activities that most significantly impact the economic performance of these VIEs and the Company is not the primary beneficiary; accordingly, it has not consolidated these VIEs.
Equity Method Investments	The Company’s investments in entities for which the Company does not have a controlling interest and for which it is not the primary beneficiary, 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. Equity method investments are recorded as other long-term assets. Income or loss from these investments is recorded as a separate line item in the statements of operations. Intercompany profits or losses associated with the Company’s equity method investments are eliminated until realized by the investee in transactions with third parties. Distributions received from equity method investees are reflected in the statements of cash flows using the nature of distributions approach, under which distributions are classified based on the nature of the activity that generated them.
Unicorporated Entities, Proportional Consolidation	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.
Other Equity Investments With Readily Determinable Fair Values	Under the new guidance, which was applicable to the Company on a prospective basis, equity investments, other than those accounted for as equity method investments or those that are proportionately consolidated, are measured at fair value if their fair values are readily determinable.
Other Equity Investments Without Readily Determinable Fair Values	Equity investments that do not have readily determinable fair values are measured at cost, adjusted for changes from observable market transactions, less impairment (“adjusted cost basis”). The Company evaluates its investments for impairment by considering a variety of factors, including the earnings capacity of the related investments. Fair value measurements for the Company’s equity investments are classified within Level 3 of the fair value hierarchy based on the nature of the fair value inputs. Realized and unrealized gains or losses are recognized in other income or expense.
Property and Equipment	Property and equipment are recorded at cost, or, if acquired in a business combination, at the acquisition date fair value. Certain costs incurred in connection with developing or obtaining internal-use software are capitalized within office furniture and equipment. Depreciation and amortization of long-lived assets is computed using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are depreciated over the shorter of the term of the lease or the estimated useful lives of the improvements. Property and equipment under capital leases are depreciated over their estimated useful lives. Expenditures for repairs and maintenance are charged to expense as incurred. Expenditures for betterments and major improvements that extend the life of the related assets are capitalized and depreciated over the remaining useful lives of the assets. The carrying amounts of assets sold or retired and the related accumulated depreciation are eliminated in the year of disposal, with resulting gains or losses included in other income or expense.
Finite-Lived Intangible Assets	Acquired intangible assets that have finite lives are amortized over their useful lives, which are generally based on contractual or legal rights. Finite-lived intangible assets are amortized in a manner consistent with the pattern in which the related benefits are expected to be consumed.
Impairment of Long-Lived Assets	Management reviews long-lived assets for impairment whenever events or changes in circumstances indicate that their carrying amounts may not be recoverable. If an evaluation is required, the estimated future undiscounted cash flows associated with the asset are compared with the asset’s carrying amount to determine if there has been an impairment, which is calculated as the difference between the fair value of an asset and its carrying value. Estimates of future undiscounted cash flows are based on expected revenue and operating costs for the business as well as anticipated future economic conditions. Fair values take into consideration management’s estimates of risk-adjusted discount rates, which are believed to be consistent with assumptions that marketplace participants would use in their estimates of fair value.
Goodwill and Indefinite-Lived Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets The Company has goodwill and certain indefinite-lived intangible assets that have been recorded in connection with its acquisitions of businesses. Goodwill and indefinite-lived intangible assets are not amortized, but instead are tested for impairment at least annually. The Company performs its annual impairment tests of goodwill and indefinite-lived intangible assets during the fourth quarter of each year, and on a quarterly basis, monitors these assets for potential indicators of impairment. Goodwill is required to be tested for impairment at the reporting unit level. A reporting unit is an operating segment or one level below the operating segment level, which is referred to as a component. Management identifies its reporting units by assessing whether components (i) have discrete financial information available; (ii) engage in business activities; and (iii) have a segment manager regularly review the component’s operating results. If two or more components are deemed economically similar, those components are aggregated into one reporting unit when performing the annual goodwill impairment test.
Business Combinations	Business Combinations The determination of the fair value of net assets acquired in a business combination requires estimates and judgments of future cash flow expectations for the acquired business and the related identifiable tangible and intangible assets. Fair values are calculated using expected cash flows and industry-standard valuation techniques. For current assets and current liabilities, book value is generally assumed to equal fair value. Goodwill is the amount by which consideration paid exceeds the fair value of acquired net assets. Acquisition costs, including acquisition integration costs, are expensed as incurred and are included within general and administrative expenses in the consolidated statements of operations. Due to the time required to gather and analyze the necessary data for each acquisition, U.S. GAAP provides a “measurement period” of up to one year in which to finalize these fair value determinations. During the measurement period, preliminary fair value estimates may be revised if new information is obtained about the facts and circumstances existing as of the date of acquisition, or based on the final net assets and working capital of the acquired business, as prescribed in the applicable purchase agreement. Such adjustments may result in the recognition, or adjust the fair values, of acquisition-related assets and liabilities and/or consideration paid, and are referred to as “measurement period” adjustments. Other revisions to these fair value estimates are reflected as income or expense, as appropriate. Consideration paid generally consists of cash, common stock and potential future payments that are contingent upon the acquired business achieving certain levels of earnings in the future, also referred to as “acquisition-related contingent consideration” or “earn-outs.” Earn-out liabilities are measured at their estimated fair values as of the date of acquisition. Subsequent to the date of acquisition, if future earn-out payments are expected to differ from earn-out payments estimated as of the date of acquisition, any related fair value adjustments are recognized in the period that such expectation is considered probable. Changes in the fair value of earn-out liabilities, other than those related to measurement period adjustments, as described above, are recorded within other income or expense in the consolidated statements of operations. Fair values are estimated using income approaches such as discounted cash flows or option pricing models. Acquisition-related contingent consideration is included within other current and other long-term liabilities, as appropriate, within the consolidated balance sheets.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs relate to the Company’s debt instruments, the short and long-term portions of which are reflected as deductions from the carrying amounts of the related debt instrument, including the Company’s credit facility. Deferred financing costs are amortized over the terms of the related debt instruments using the effective interest method.
Self-Insurance	Self-Insurance The Company is self-insured up to the amount of its deductible for its insurance policies. MasTec maintains insurance policies subject to per claim deductibles of $1.5 million for its workers’ compensation policy, $3.0 million for its general liability policy and $3.0 million for its automobile liability policy. In addition, the Company has excess umbrella coverage. Liabilities under these insurance programs are accrued based upon management’s estimates of the ultimate liability for claims reported and an estimate of claims incurred but not reported, with assistance from third-party actuaries. MasTec also maintains an insurance policy with respect to employee group medical claims, which is subject to annual per employee maximum losses of $0.5 million. MasTec’s estimated liability for employee group medical claims is based on statistical analysis of historical claims experience and specific knowledge of actual losses that have occurred. The Company is required to post collateral, generally in the form of letters of credit, surety bonds and cash to certain of its insurance carriers. Cash collateral deposited with insurance carriers is included in other long-term assets in the consolidated balance sheets. The present value of the Company’s self-insurance liability is reflected in the consolidated balance sheets within current and other long-term liabilities, as appropriate. The determination of such claims and expenses and the appropriateness of the related liability is reviewed and updated quarterly. These insurance liabilities are, however, difficult to assess and estimate due to many factors, the effects of which are often unknown or difficult to estimate, including the severity of an injury, the determination of the Company’s liability in proportion to other parties’ liability and the number of incidents not reported. Accruals are based upon known facts and historical trends. Although management believes its accruals are adequate, a change in experience or actuarial assumptions could materially affect the Company’s results of operations in a particular period.
Income Taxes	Income Taxes The Company records income taxes using the asset and liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the financial statement and income tax basis of the Company’s assets and liabilities. Income taxes are estimated in each of the jurisdictions in which the Company operates. This process involves estimating the tax exposure, together with assessing temporary differences resulting from differing treatment of items, such as deferred revenue, for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included, net, within the consolidated balance sheets as long-term assets and/or liabilities, as appropriate. The recording of a deferred tax asset assumes the realization of such asset in the future. Otherwise, a valuation allowance is recorded to reduce the asset to its estimated net realizable value. If management determines that the Company may not be able to realize all or part of a deferred tax asset in the future, a valuation allowance for the deferred tax asset is charged to income tax expense in the period the determination is made. Management considers future pretax income and ongoing prudent and feasible tax planning strategies in assessing the estimated net realizable value of tax assets and the corresponding need for any related valuation allowances. In determining the provision for income taxes, management uses an effective tax rate based on annual pre-tax income, statutory tax rates, permanent tax differences and tax planning opportunities in the various jurisdictions in which the Company operates. As a result of the 2017 Tax Act, the Company will generally be free of additional U.S. federal tax consequences on distributed foreign subsidiary earnings due to a dividends received deduction implemented as part of the move to a territorial tax system. The Company has generally not provided for U.S. income taxes on unremitted foreign earnings because such earnings are considered to be insignificant. Significant factors that affect the annual effective tax rate include management’s assessment of certain tax matters, the location and amount of taxable earnings, changes in certain non-deductible expenses and expected credits. In December 2017, the “2017 Tax Act” was enacted, which included broad tax reform that was applicable to the Company. See Note 12 - Income Taxes for additional discussion. The Company and its subsidiaries file income tax returns in numerous tax jurisdictions, including U.S. federal, most U.S. states and certain foreign jurisdictions. Although management believes its calculations for tax returns are correct and the positions taken thereon are reasonable, the final outcome of income tax examinations could be materially different from the resolution management currently anticipates and the estimates that are reflected in the Company’s consolidated financial statements, which could materially affect the Company’s results of operations, cash flows and liquidity in a particular period. To the extent interest and penalties are assessed by taxing authorities, such amounts are accrued and included within income tax expense.
Stock-Based Compensation	Stock-Based Compensation The Company has certain stock-based compensation plans, under which restricted stock awards and restricted stock units (together “restricted shares”) are available for issuance to eligible participants. Non-cash stock-based compensation expense is included within general and administrative expense in the consolidated statements of operations. Share-based payments, to the extent they are compensatory, are recognized based on their grant date fair values. Forfeitures are recorded as they occur. The Company records a deferred tax asset, or future tax benefit, based on the amount of share-based compensation recognized in the financial statements over the vesting period of share-based awards. The tax effects of differences between the fair value of a share-based award on the date of vesting and the date of grant, also referred to as excess tax benefits or tax deficiencies, are recognized within the provision for income taxes in the period such vestings occur. Grants of restricted shares are valued based on the closing market share price of MasTec’s common stock as reported on the New York Stock Exchange (the “market price”) on the date of grant. Compensation expense arising from restricted shares is recognized on a straight line basis over the vesting period. Grants of restricted shares have cliff vesting terms, which generally vest over a period of 3 years. Upon vesting, some of the underlying shares may be sold to cover the required tax withholdings. However, some participants may choose the net share settlement method to cover withholding tax requirements, in which case shares are not issued, but are treated as common stock repurchases in the consolidated financial statements, as they reduce the number of shares that would have been issued upon vesting. The Company then pays the corresponding withholding taxes to the appropriate taxing authorities in cash on behalf of the recipient. Withheld shares, which are valued at the market price on the date of vesting, are recorded as a reduction to additional paid-in capital and are reflected within financing activities in the consolidated statements of cash flows. Shares withheld in connection with stock-based compensation arrangements totaled approximately 96,739, 138,519, and 44,988 for the years ended December 31, 2018, 2017 and 2016, respectively, and payments to taxing authorities for withheld shares totaled $3.8 million, $6.2 million and $0.6 million, respectively. The Company has certain employee stock purchase plans (collectively, “ESPPs”) under which shares of the Company’s common stock are available for purchase by eligible participants. These plans allow participants to purchase MasTec, Inc. common stock at 85% of its fair market value at the lower of (i) the date of commencement of the offering period or (ii) the last day of the exercise period, as defined in the plan documents. The fair value of purchases under the Company’s employee stock purchase plans is estimated using the Black-Scholes option-pricing valuation model. The determination of fair value of stock-based awards using an option-pricing model is affected by the Company’s stock price as well as assumptions pertaining to several variables, including expected stock price volatility, the expected term of the award and the risk-free rate of interest. In the option-pricing model for the Company’s employee stock purchase plans, expected stock price volatility is based on historical volatility of the Company’s common stock. The expected term of the award is based on historical and expected exercise patterns and the risk-free rate of interest is based on U.S. Treasury yields. The Company has not paid dividends in the past, and does not anticipate paying dividends in the foreseeable future, and therefore uses an expected dividend yield of zero.
Collective Bargaining Agreements and Multiemployer Plans	Collective Bargaining Agreements and Multiemployer Plans Certain of MasTec’s subsidiaries, including certain subsidiaries in Canada, are party to various collective bargaining agreements with unions representing certain of their employees. These agreements require the subsidiaries party to the agreements to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multiemployer pension and other multiemployer benefit plans and trusts (“MEPPs”). These contributions are recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization. Contributions are generally based on fixed amounts per hour per employee for employees covered under these plans. Multiemployer plan contribution rates are determined annually and assessed on a “pay-as-you-go” basis based on union employee payrolls. The Pension Protection Act of 2006, as amended, (the “PPA”) requires pension plans that are underfunded to improve their funding ratios within prescribed intervals based on their level of underfunding, under which benefit reductions may apply and/or participating employers could be required to make additional contributions. In addition, if a multiemployer defined benefit plan fails to satisfy certain minimum funding requirements, the IRS may impose on the employers contributing to such plans a non-deductible excise tax of 5% of the amount of the accumulated funding deficiency. Union payrolls cannot be determined for future periods because the number of union employees employed at any given time, and the plans in which they may participate, vary depending upon the location and number of ongoing projects at a given time and the need for union resources in connection with those projects. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to the ones contained in the expiring agreements. Under current law pertaining to employers that are contributors to U.S.-registered multiemployer defined benefit plans, a plan’s termination, an employer’s voluntary withdrawal from, or the mass withdrawal of contributing employers from, an underfunded multiemployer defined benefit plan requires participating employers to make payments to the plan for their proportionate share of the multiemployer plan’s unfunded vested liabilities. These liabilities include an allocable share of the unfunded vested benefits of the plan for all plan participants, not only for benefits payable to participants of the contributing employer. As a result, participating employers may bear a higher proportion of liability for unfunded vested benefits if the other participating employers cease to contribute to, or withdraw from, the plan. The allocable portion of liability to participating employers could be more disproportionate if employers that have withdrawn from the plan are insolvent, or if they otherwise fail to pay their proportionate share of the withdrawal liability. If the Company is subject to a withdrawal liability, the related withdrawal charge is recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization, with any related liability recorded within other current and/or other long-term liabilities, as appropriate. The Company’s participation in the multiemployer pension plans is evaluated by management on an ongoing basis.
Restructuring Activities	Restructuring Activities From time to time, the Company may incur costs to streamline its business operations. These streamlining efforts, which are designed to improve profitability, could include eliminating service offerings that no longer fit into the Company’s business plan, certain integration activities for acquired businesses, reducing or eliminating services or operations that do not produce adequate revenue or margins, or reducing costs of business units that need margin improvements. The costs associated with these efforts, which the Company refers to as restructuring charges, include such items as employee separation costs, lease termination expenses and losses on disposal of excess fixed assets. When these efforts are related to circumstances that are significant, unique in nature and outside of the course of the Company’s normal and periodic business streamlining efforts, the related amount of restructuring charges included within the consolidated financial statements is aggregated and accompanied by a discussion of the nature of such restructuring activities. Restructuring charges are included within the applicable line item(s) in the consolidated statement of operations based on the nature of the expense incurred.
Litigation and Contingencies	Litigation and Contingencies Accruals for litigation and contingencies are reflected in the consolidated financial statements based on management’s assessment, including advice of legal counsel, of the expected outcome of litigation or other dispute resolution proceedings and/or the expected resolution of contingencies. Liabilities for estimated losses are accrued if the potential loss from any claim or legal proceeding is considered probable and the amount can be reasonably estimated. Significant judgment is required in both the determination of probability of loss and the determination as to whether the amount is reasonably estimable. Accruals are based only on information available at the time of the assessment due to the uncertain nature of such matters. As additional information becomes available, management reassesses potential liabilities related to pending claims and litigation and may revise its previous estimates, which could materially affect the Company’s results of operations in a given period.
Recent Accounting Pronouncements	Recent Accounting Pronouncements See the revenue recognition discussion within Significant Accounting Policies above, and the recent accounting pronouncements discussion below, for information pertaining to the effects of recently adopted and other recent accounting pronouncements. Other Accounting Pronouncements Adopted in 2018 In August 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”) to reduce diversity in practice by providing guidance on the classification of certain cash receipts and payments in the statement of cash flows. This ASU, which the Company adopted as of January 1, 2018, is effective on a retrospective basis, and resulted in the reclassification of $12 million of acquisition-related contingent consideration payments in excess of acquisition date liabilities from financing to operating cash flows for the year ended December 31, 2017. The other provisions of this ASU did not have a material effect on the Company’s consolidated financial statements. Accounting Pronouncements To Be Adopted in 2019 In February 2016, the 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 will 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 new guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. The Company will adopt ASU 2016-02 during the first quarter of 2019 using the modified retrospective method. The new guidance will be applied to leases that exist or are entered into on or after January 1, 2019, without adjusting comparative periods in the financial statements. The Company elected to utilize the package of practical expedients that allows entities to (1) not reassess whether any expired or existing contracts are or contain leases; (2) retain the existing classification of lease contracts as of the date of adoption; and (3) not reassess initial direct costs for any existing leases. The Company is in the final stages of evaluating its existing lease portfolio and is continuing to assess and quantify the value of right-of-use assets and lease liabilities that will be included on its balance sheet as of January 1, 2019. The Company is finalizing its implementation of a new lease accounting and administration software solution to manage and account for leases under the new guidance and is updating certain of its business processes and internal controls to meet the reporting and disclosure requirements of the new standard. The new guidance is not expected to materially affect the amount of expense recognized under the Company’s current leasing arrangements, however, based on its review to date of existing lease contracts, the Company expects the amount of incremental lease assets and liabilities to be recognized on its consolidated balance sheets for operating leases will be between $200 million and $230 million. The adoption of Topic 842 is not expected to have a material effect on the Company's results of operations or cash flows. For information about the Company’s future lease commitments as of December 31, 2018, see Note 8 - Lease Obligations. In August 2018, the SEC issued Release No. 33-10532, Disclosure Update and Simplification, which amends and clarifies certain financial reporting disclosure requirements. The principal change from this new guidance will be the inclusion of a statement of changes in shareholders' equity in the Company’s interim consolidated financial statements beginning with the quarter ended March 31, 2019. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718) - Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). ASU 2018-07 expands the guidance in Topic 718 to include share-based payments for goods and services to non-employees and generally aligns it with the guidance for share-based payments to employees. ASU 2018-07 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The adoption of this ASU is not expected to have a material effect on the Company’s consolidated financial statements. 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 permits 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 guidance may be applied retrospectively or in the period of adoption. ASU 2018-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. The Company will adopt ASU 2018-02 during the first quarter of 2019 and continues to evaluate its policy election and the related effect of this ASU on its consolidated financial statements, which is not expected to be material. Other Recent Accounting Pronouncements In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”) to reduce diversity in practice in accounting for the costs of implementing cloud computing arrangements that are service contracts. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the requirements for internal-use software. Accounting for the service element of the cloud computing arrangement is not affected by the new guidance. Under ASU 2018-15, amortization expense, payments for and asset balances related to such capitalized implementation costs are to be presented within the same line items of the entity’s statements of operations, cash flows and balance sheets, respectively, as the related service fee activity and balances would be presented. ASU 2018-15 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). ASU 2018-13, which is intended to improve the effectiveness of fair value measurement disclosures, modifies the disclosure requirements for certain estimates and assumptions used in determining the fair value of assets and liabilities. ASU 2018-13 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 introduced an expected credit loss methodology for the measurement and recognition of credit losses on most financial assets, including trade and financing receivables. The expected credit loss methodology under ASU 2016-13, which is based on historical experience, current conditions and reasonable and supportable forecasts, replaces the probable/incurred loss model for measuring and recognizing expected losses under current GAAP. ASU 2016-13 also requires enhanced disclosures pertaining to significant estimates and judgments used in estimating credit losses under the expected credit loss methodology. ASU 2016-13 and its related clarifying assumptions are effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements.
Comprehensive Income	Comprehensive Income and Accumulated Other Comprehensive Loss Comprehensive income (loss) is a measure of net income (loss) and other changes in equity that result from transactions other than those with shareholders. Comprehensive income (loss) and related accumulated comprehensive income (loss) balances, consist of net income (loss), foreign currency translation adjustments, primarily from fluctuations in foreign currency exchange rates of the Company’s foreign subsidiaries with a functional currency other than the U.S. dollar, unrealized gains and losses from certain investment activities and net income (loss) attributable to non-controlling interests.
Income Tax Uncertainties	An entity may only recognize or continue to recognize tax positions that meet a "more likely than not" threshold. In the ordinary course of business, there is inherent uncertainty in quantifying income tax positions. The Company assesses its income tax positions and records tax benefits for all years subject to examination based on management's evaluation of the facts, circumstances and information available at the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company has recognized the largest amount of tax benefit with a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, no tax benefit has been recognized in the Company's financial statements.