Summary of Significant Accounting Policies	12 Months Ended
Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation The financial statements of Trinity Industries, Inc. and its consolidated subsidiaries (“Trinity,” “Company,” “we” or “our”) include the accounts of its wholly-owned subsidiaries and its partially-owned subsidiaries, TRIP Rail Holdings LLC ("TRIP Holdings") and RIV 2013 Rail Holdings LLC ("RIV 2013"), in which the Company has a controlling interest. All significant intercompany accounts and transactions have been eliminated. Stockholders' Equity On May 5, 2014, the Company's Board of Directors authorized a 2-for-1 stock split on its common shares in the form of a 100% stock dividend. The additional shares were distributed on June 19, 2014, to shareholders of record at the close of business on June 5, 2014. The stock split is reflected in the consolidated statement of stockholders' equity by the reclassification of $78.0 million from "Capital in Excess of Par Value" to "Common Stock" representing the par value of the additional shares issued. In December 2015, the Company’s Board of Directors renewed its $250 million share repurchase program effective January 1, 2016 through December 31, 2017. The new program replaced the previous program which expired on December 31, 2015. Under the new program, 2,070,600 shares were repurchased during the year ended December 31, 2016, at a cost of $34.7 million. During the year ended December 31, 2015, the Company repurchased 3,947,320 shares at a cost of $115.0 million. In May 2015, the Company's stockholders approved amendments to the Company's Certificate of Incorporation increasing the number of authorized shares of common stock from 200 million to 400 million and reducing the par value of the Company's common stock to $0.01 per share from $1.00 per share. Revenue Recognition Revenues for contracts providing for a large number of units and few deliveries are recorded as the individual units are produced, inspected, and accepted by the customer as the risk of loss passes to the customer upon delivery acceptance on these contracts. Revenue from rentals and operating leases, including contracts that contain non-level fixed rental payments, is recognized monthly on a straight-line basis. Revenue is recognized from the sales of railcars from the lease fleet on a gross basis in leasing revenues and cost of revenues if the railcar has been owned for one year or less at the time of sale. Sales of railcars from the lease fleet owned for more than one year are recognized as a net gain or loss from the disposal of a long-term asset. Fees for shipping and handling are recorded as revenue. For all other products, we recognize revenue when products are shipped or services are provided. Income Taxes The liability method is used to account for income taxes. Deferred income taxes represent the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Valuation allowances reduce deferred tax assets to an amount that will more likely than not be realized. The Company regularly evaluates the likelihood of realization of tax benefits derived from positions it has taken in various federal and state filings after consideration of all relevant facts, circumstances, and available information. For those tax positions that are deemed more likely than not to be sustained, the Company recognizes the benefit it believes is cumulatively greater than 50% likely to be realized. To the extent the Company were to prevail in matters for which accruals have been established or be required to pay amounts in excess of recorded reserves, the effective tax rate in a given financial statement period could be materially impacted. Financial Instruments The Company considers all highly liquid debt instruments to be either cash and cash equivalents if purchased with a maturity of three months or less, or short-term marketable securities if purchased with a maturity of more than three months and less than one year. The Company intends to hold its short-term marketable securities until they are redeemed at their maturity date and believes that under the "more likely than not" criteria, the Company will not be required to sell the securities before recovery of their amortized cost bases, which may be maturity. Financial instruments that potentially subject the Company to a concentration of credit risk are primarily cash investments including restricted cash, short-term marketable securities, and receivables. The Company places its cash investments and short-term marketable securities in bank deposits and investment grade, short-term debt instruments and limits the amount of credit exposure to any one commercial issuer. Concentrations of credit risk with respect to receivables are limited due to control procedures that monitor the credit worthiness of customers, the large number of customers in the Company's customer base, and their dispersion across different industries and geographic areas. As receivables are generally unsecured, the Company maintains an allowance for doubtful accounts based upon the expected collectibility of all receivables. Receivable balances determined to be uncollectible are charged against the allowance. The carrying values of cash, short-term marketable securities (using level two inputs), receivables, and accounts payable are considered to be representative of their respective fair values. At December 31, 2016, one Rail Group customer's net receivable balance, substantially all paid subsequent to December 31, 2016, accounted for 21% of the consolidated net receivables balance outstanding. Inventories Inventories are valued at the lower of cost or market, with cost determined principally on the first in first out method. Market is replacement cost or net realizable value. Work in process and finished goods include material, labor, and overhead. Property, Plant, and Equipment Property, plant, and equipment are stated at cost and depreciated over their estimated useful lives using the straight-line method. The estimated useful lives are: buildings and improvements - 3 to 30 years; leasehold improvements - the lesser of the term of the lease or 7 years; machinery and equipment - 2 to 10 years; information systems hardware and software - 2 to 5 years; and railcars in our lease fleet - generally 35 years. The costs of ordinary maintenance and repair are charged to operating costs. Long-lived Assets The Company periodically evaluates the carrying value of long-lived assets to be held and used for potential impairment. The carrying value of long-lived assets to be held and used is considered impaired only when their carrying value is not recoverable through undiscounted future cash flows and the fair value of the assets is less than their carrying value. Fair value is determined primarily using the anticipated cash flows discounted at a rate commensurate with the risks involved or market quotes as available. Impairment losses on long-lived assets held for sale are determined in a similar manner, except that fair values are reduced by the estimated cost to dispose of the assets. Based on the Company's evaluations, no impairment charges were determined to be necessary as of December 31, 2016 and 2015. Goodwill and Intangible Assets Goodwill is required to be tested for impairment annually, or on an interim basis whenever events or circumstances change, indicating that the carrying amount of the goodwill might be impaired. The quantitative goodwill impairment test is a two-step process with step one requiring the comparison of the reporting unit's estimated fair value with the carrying amount of its net assets. If necessary, step two of the impairment test determines the amount of goodwill impairment to be recorded when the reporting unit's recorded net assets exceed its fair value. Impairment is assessed at the “reporting unit” level by applying a fair value-based test for each unit with recorded goodwill. The estimates and judgments that most significantly affect the fair value calculations are assumptions, consisting of level three inputs, related to revenue and operating profit growth, discount rates and exit multiples. As of December 31, 2016 and 2015, the Company's annual impairment test of goodwill was completed at the reporting unit level and no impairment charges were determined to be necessary. The net book value of intangible assets totaled $79.7 million and $86.9 million as of December 31, 2016 and 2015, respectively, and included intangible assets with defined useful lives of $43.1 million and $50.3 million, respectively, which are amortized over their estimated useful lives ranging from 1 to 20 years. Intangible assets were evaluated for potential impairment as of December 31, 2016 and 2015. Restricted Cash Restricted cash consists of cash and cash equivalents held either as collateral for the Company's non-recourse debt and lease obligations or as security for the performance of certain product sales agreements. As such, they are restricted in use. Insurance The Company is effectively self-insured for workers' compensation claims. A third party administrator is used to process claims. We accrue our workers' compensation liability based upon independent actuarial studies. Warranties The Company provides various express, limited product warranties that generally range from one to five years depending on the product. The warranty costs are estimated using a two-step approach. First, an engineering estimate is made for the cost of all claims that have been asserted by customers. Second, based on historical, accepted claims experience, a cost is accrued for all products still within a warranty period for which no claims have been filed. The Company provides for the estimated cost of product warranties at the time revenue is recognized related to products covered by warranties, and assesses the adequacy of the resulting reserves on a quarterly basis. Foreign Currency Translation Certain operations outside the United States prepare financial statements in currencies other than the United States dollar. The income statement amounts are translated at average exchange rates for the year, while the assets and liabilities are translated at year-end exchange rates. Translation adjustments are accumulated as a separate component of stockholders' equity and other comprehensive income. The functional currency of our Mexico operations is considered to be the United States dollar. The functional currency of our Canadian operations is considered to be the Canadian dollar. Other Comprehensive Income (Loss) Other comprehensive net income (loss) consists of foreign currency translation adjustments, the effective unrealized gains and losses on the Company's derivative financial instruments, and the net actuarial gains and losses of the Company's defined benefit plans, the sum of which, along with net income (loss), constitutes comprehensive net income (loss). See Note 15 Accumulated Other Comprehensive Loss (“AOCL”). All components are shown net of tax. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2014-09, "Revenue from Contracts with Customers," ("ASU 2014-09") providing common revenue recognition guidance for U.S. GAAP. Under ASU 2014-09, an entity recognizes revenue when it transfers promised goods or services to customers in an amount that reflects what it expects in exchange for the goods or services. It also requires additional detailed disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2017. The Company plans to adopt ASU 2014-09 effective January 1, 2018 using the modified retrospective method of adoption. Under this method, the guidance will be applied only to the most current period presented in the financial statements and the cumulative effect of initially applying the standard will result in an adjustment to the opening balance of retained earnings as of the date of adoption. Using both internal and external resources, the Company continues to evaluate the requirements of the standard and their application to our various business units. While our technical analysis is on-going, we anticipate a change in the timing of revenue recognition for our wind towers and utility structures product lines within our Energy Equipment Group, no longer recognizing revenue when products are delivered, but under the new guidance, recognizing revenue over time as products are manufactured. The impact of this change cannot be reasonably estimated at this time. We expect revenue recognition policies related to our other business segments to remain substantially unchanged as a result of adopting ASU 2014-09, although this could change based on our on-going analysis. Additionally, we do not anticipate significant changes in business processes or systems. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, "Leases", ("ASU 2016-02") which amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2018 with early adoption permitted. The Company plans to adopt ASU 2016-02 effective January 1, 2019. We are continuing to assess the potential effects of the new standard, including its effects on our consolidated financial statements and the accounting for revenue from full service leases. In March 2016, the FASB issued Accounting Standards Update No. 2016-09, "Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting", ("ASU 2016-09") which changes how companies account for certain aspects of share-based payments to employees. Excess tax benefits or deficiencies related to vested awards, previously recognized in stockholders' equity, will be required to be recognized in the income statement when the awards vest. ASU 2016-09 became effective for public companies during interim and annual reporting periods beginning after December 15, 2016 with early adoption permitted. Accordingly, the Company adopted this new standard on January 1, 2017. The effect of adopting this standard will result in volatility in the provision for income taxes depending on fluctuations in the price of the Company's stock. In December 2016, the FASB issued Accounting Standards Update No. 2016-18, "Restricted Cash", ("ASU 2016-18") which clarifies how entities should present restricted cash and restricted cash equivalents in the statement of cash flows. The new guidance requires a reconciliation of totals in the statement of cash flows to the related cash and cash equivalents and restricted cash captions in the balance sheet. ASU 2016-18 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2017 with early adoption permitted. The Company plans to adopt ASU 2016-18 effective January 1, 2018. Management's Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Summary of Significant Accounting Policies

Principles of Consolidation

The financial statements of Trinity Industries, Inc. and its consolidated subsidiaries (“Trinity,” “Company,” “we” or “our”) include the accounts of its wholly-owned subsidiaries and its partially-owned subsidiaries, TRIP Rail Holdings LLC ("TRIP Holdings") and RIV 2013 Rail Holdings LLC ("RIV 2013"), in which the Company has a controlling interest. All significant intercompany accounts and transactions have been eliminated.

Stockholders' Equity

On May 5, 2014, the Company's Board of Directors authorized a 2-for-1 stock split on its common shares in the form of a 100% stock dividend. The additional shares were distributed on June 19, 2014, to shareholders of record at the close of business on June 5, 2014. The stock split is reflected in the consolidated statement of stockholders' equity by the reclassification of $78.0 million from "Capital in Excess of Par Value" to "Common Stock" representing the par value of the additional shares issued.

In December 2015, the Company’s Board of Directors renewed its $250 million share repurchase program effective January 1, 2016 through December 31, 2017. The new program replaced the previous program which expired on December 31, 2015. Under the new program, 2,070,600 shares were repurchased during the year ended December 31, 2016, at a cost of $34.7 million. During the year ended December 31, 2015, the Company repurchased 3,947,320 shares at a cost of $115.0 million.

In May 2015, the Company's stockholders approved amendments to the Company's Certificate of Incorporation increasing the number of authorized shares of common stock from 200 million to 400 million and reducing the par value of the Company's common stock to $0.01 per share from $1.00 per share.

Revenue Recognition

Revenues for contracts providing for a large number of units and few deliveries are recorded as the individual units are produced, inspected, and accepted by the customer as the risk of loss passes to the customer upon delivery acceptance on these contracts. Revenue from rentals and operating leases, including contracts that contain non-level fixed rental payments, is recognized monthly on a straight-line basis. Revenue is recognized from the sales of railcars from the lease fleet on a gross basis in leasing revenues and cost of revenues if the railcar has been owned for one year or less at the time of sale. Sales of railcars from the lease fleet owned for more than one year are recognized as a net gain or loss from the disposal of a long-term asset. Fees for shipping and handling are recorded as revenue. For all other products, we recognize revenue when products are shipped or services are provided.

Income Taxes

The liability method is used to account for income taxes. Deferred income taxes represent the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Valuation allowances reduce deferred tax assets to an amount that will more likely than not be realized.

The Company regularly evaluates the likelihood of realization of tax benefits derived from positions it has taken in various federal and state filings after consideration of all relevant facts, circumstances, and available information. For those tax positions that are deemed more likely than not to be sustained, the Company recognizes the benefit it believes is cumulatively greater than 50% likely to be realized. To the extent the Company were to prevail in matters for which accruals have been established or be required to pay amounts in excess of recorded reserves, the effective tax rate in a given financial statement period could be materially impacted.

Financial Instruments

The Company considers all highly liquid debt instruments to be either cash and cash equivalents if purchased with a maturity of three months or less, or short-term marketable securities if purchased with a maturity of more than three months and less than one year. The Company intends to hold its short-term marketable securities until they are redeemed at their maturity date and believes that under the "more likely than not" criteria, the Company will not be required to sell the securities before recovery of their amortized cost bases, which may be maturity.

Financial instruments that potentially subject the Company to a concentration of credit risk are primarily cash investments including restricted cash, short-term marketable securities, and receivables. The Company places its cash investments and short-term marketable securities in bank deposits and investment grade, short-term debt instruments and limits the amount of credit exposure to any one commercial issuer. Concentrations of credit risk with respect to receivables are limited due to control procedures that monitor the credit worthiness of customers, the large number of customers in the Company's customer base, and their dispersion across different industries and geographic areas. As receivables are generally unsecured, the Company maintains an allowance for doubtful accounts based upon the expected collectibility of all receivables. Receivable balances determined to be uncollectible are charged against the allowance. The carrying values of cash, short-term marketable securities (using level two inputs), receivables, and accounts payable are considered to be representative of their respective fair values. At December 31, 2016, one Rail Group customer's net receivable balance, substantially all paid subsequent to December 31, 2016, accounted for 21% of the consolidated net receivables balance outstanding.

Inventories

Inventories are valued at the lower of cost or market, with cost determined principally on the first in first out method. Market is replacement cost or net realizable value. Work in process and finished goods include material, labor, and overhead.

Property, Plant, and Equipment

Property, plant, and equipment are stated at cost and depreciated over their estimated useful lives using the straight-line method. The estimated useful lives are: buildings and improvements - 3 to 30 years; leasehold improvements - the lesser of the term of the lease or 7 years; machinery and equipment - 2 to 10 years; information systems hardware and software - 2 to 5 years; and railcars in our lease fleet - generally 35 years. The costs of ordinary maintenance and repair are charged to operating costs.

Long-lived Assets

The Company periodically evaluates the carrying value of long-lived assets to be held and used for potential impairment. The carrying value of long-lived assets to be held and used is considered impaired only when their carrying value is not recoverable through undiscounted future cash flows and the fair value of the assets is less than their carrying value. Fair value is determined primarily using the anticipated cash flows discounted at a rate commensurate with the risks involved or market quotes as available. Impairment losses on long-lived assets held for sale are determined in a similar manner, except that fair values are reduced by the estimated cost to dispose of the assets. Based on the Company's evaluations, no impairment charges were determined to be necessary as of December 31, 2016 and 2015.

Goodwill and Intangible Assets

Goodwill is required to be tested for impairment annually, or on an interim basis whenever events or circumstances change, indicating that the carrying amount of the goodwill might be impaired. The quantitative goodwill impairment test is a two-step process with step one requiring the comparison of the reporting unit's estimated fair value with the carrying amount of its net assets. If necessary, step two of the impairment test determines the amount of goodwill impairment to be recorded when the reporting unit's recorded net assets exceed its fair value. Impairment is assessed at the “reporting unit” level by applying a fair value-based test for each unit with recorded goodwill. The estimates and judgments that most significantly affect the fair value calculations are assumptions, consisting of level three inputs, related to revenue and operating profit growth, discount rates and exit multiples. As of December 31, 2016 and 2015, the Company's annual impairment test of goodwill was completed at the reporting unit level and no impairment charges were determined to be necessary.

The net book value of intangible assets totaled $79.7 million and $86.9 million as of December 31, 2016 and 2015, respectively, and included intangible assets with defined useful lives of $43.1 million and $50.3 million, respectively, which are amortized over their estimated useful lives ranging from 1 to 20 years. Intangible assets were evaluated for potential impairment as of December 31, 2016 and 2015.

Restricted Cash

Restricted cash consists of cash and cash equivalents held either as collateral for the Company's non-recourse debt and lease obligations or as security for the performance of certain product sales agreements. As such, they are restricted in use.

Insurance

The Company is effectively self-insured for workers' compensation claims. A third party administrator is used to process claims. We accrue our workers' compensation liability based upon independent actuarial studies.

Warranties

The Company provides various express, limited product warranties that generally range from one to five years depending on the product. The warranty costs are estimated using a two-step approach. First, an engineering estimate is made for the cost of all claims that have been asserted by customers. Second, based on historical, accepted claims experience, a cost is accrued for all products still within a warranty period for which no claims have been filed. The Company provides for the estimated cost of product warranties at the time revenue is recognized related to products covered by warranties, and assesses the adequacy of the resulting reserves on a quarterly basis.

Foreign Currency Translation

Certain operations outside the United States prepare financial statements in currencies other than the United States dollar. The income statement amounts are translated at average exchange rates for the year, while the assets and liabilities are translated at year-end exchange rates. Translation adjustments are accumulated as a separate component of stockholders' equity and other comprehensive income. The functional currency of our Mexico operations is considered to be the United States dollar. The functional currency of our Canadian operations is considered to be the Canadian dollar.

Other Comprehensive Income (Loss)

Other comprehensive net income (loss) consists of foreign currency translation adjustments, the effective unrealized gains and losses on the Company's derivative financial instruments, and the net actuarial gains and losses of the Company's defined benefit plans, the sum of which, along with net income (loss), constitutes comprehensive net income (loss). See Note 15 Accumulated Other Comprehensive Loss (“AOCL”). All components are shown net of tax.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2014-09, "Revenue from Contracts with Customers," ("ASU 2014-09") providing common revenue recognition guidance for U.S. GAAP. Under ASU 2014-09, an entity recognizes revenue when it transfers promised goods or services to customers in an amount that reflects what it expects in exchange for the goods or services. It also requires additional detailed disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. ASU 2014-09 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2017.

The Company plans to adopt ASU 2014-09 effective January 1, 2018 using the modified retrospective method of adoption. Under this method, the guidance will be applied only to the most current period presented in the financial statements and the cumulative effect of initially applying the standard will result in an adjustment to the opening balance of retained earnings as of the date of adoption.

Using both internal and external resources, the Company continues to evaluate the requirements of the standard and their application to our various business units. While our technical analysis is on-going, we anticipate a change in the timing of revenue recognition for our wind towers and utility structures product lines within our Energy Equipment Group, no longer recognizing revenue when products are delivered, but under the new guidance, recognizing revenue over time as products are manufactured. The impact of this change cannot be reasonably estimated at this time. We expect revenue recognition policies related to our other business segments to remain substantially unchanged as a result of adopting ASU 2014-09, although this could change based on our on-going analysis. Additionally, we do not anticipate significant changes in business processes or systems.

In February 2016, the FASB issued Accounting Standards Update No. 2016-02, "Leases", ("ASU 2016-02") which amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2018 with early adoption permitted. The Company plans to adopt ASU 2016-02 effective January 1, 2019. We are continuing to assess the potential effects of the new standard, including its effects on our consolidated financial statements and the accounting for revenue from full service leases.

In March 2016, the FASB issued Accounting Standards Update No. 2016-09, "Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting", ("ASU 2016-09") which changes how companies account for certain aspects of share-based payments to employees. Excess tax benefits or deficiencies related to vested awards, previously recognized in stockholders' equity, will be required to be recognized in the income statement when the awards vest. ASU 2016-09 became effective for public companies during interim and annual reporting periods beginning after December 15, 2016 with early adoption permitted. Accordingly, the Company adopted this new standard on January 1, 2017. The effect of adopting this standard will result in volatility in the provision for income taxes depending on fluctuations in the price of the Company's stock.

In December 2016, the FASB issued Accounting Standards Update No. 2016-18, "Restricted Cash", ("ASU 2016-18") which clarifies how entities should present restricted cash and restricted cash equivalents in the statement of cash flows. The new guidance requires a reconciliation of totals in the statement of cash flows to the related cash and cash equivalents and restricted cash captions in the balance sheet. ASU 2016-18 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2017 with early adoption permitted. The Company plans to adopt ASU 2016-18 effective January 1, 2018.

Management's Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.