Summary of Significant Accounting Policies	12 Months Ended
Dec. 31, 2012
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 majority-owned subsidiary, TRIP Rail Holdings LLC ("TRIP Holdings"). All significant intercompany accounts and transactions have been eliminated. Certain amounts previously reported have been adjusted in the accompanying consolidated financial statements to remove the effects of discontinued operations. See Note 2 Acquisitions and Divestitures. Stockholders' Equity In September 2012, the Company’s Board of Directors authorized a new $200 million share repurchase program, effective October 1, 2012, which expires on December 31, 2014. The new program replaced the prior program which expired on September 30, 2012. During the year ended December 31, 2012, the Company repurchased 1,834,221 shares under the prior program at a cost of $45.2 million. In 2011, an amount of $15.5 million was reclassified between capital in excess of par value and accumulated other comprehensive loss to properly reflect the additional amount of accumulated unrealized loss on derivative financial instruments attributable to the Company after the purchase of additional interests in TRIP Holdings. 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 pre-delivery acceptance on these contracts. This occurs primarily in the Rail and Inland Barge Groups. Revenue from rentals and operating leases, including contracts which 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 by the lease fleet for one year or less at the time of sale. Sales of railcars from the lease fleet that have been owned by the lease fleet 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. Financial instruments that potentially subject the Company to a concentration of credit risk are primarily cash investments, 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 collectability of all receivables. Receivable balances determined to be uncollectible are charged against the allowance. The carrying values of cash, receivables and accounts payable are considered to be representative of their respective fair values. At December 31, 2012, one customer’s net receivable balance in our Energy Equipment Group, all within terms, 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 while renewals and major replacements are capitalized. 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 for the estimated cost to dispose of the assets. Impairment losses were not material for the years ended December 31, 2012, 2011, and 2010. 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 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. Step two of the impairment test is necessary to determine 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 related to revenue and operating profit growth, discount rates and exit multiples. As of December 31, 2012 and 2011, the Company's annual impairment test of goodwill was completed at the reporting unit level and no impairment charges were determined to be necessary. Intangible assets with defined useful lives, which as of December 31, 2012 had net book values of $21.7 million, are amortized over their estimated useful lives, and were also evaluated for potential impairment as of December 31, 2012. Restricted Cash Restricted cash consists of cash and cash equivalents that are held as collateral for the Company's non-recourse debt and lease obligations and as such are restricted in use. Insurance The Company is effectively self-insured for workers' compensation. A third party administrator is used to process claims. We accrue our workers' compensation liability based upon independent actuarial studies. Warranties Depending on the product, the Company provides warranties against materials and manufacturing defects generally ranging from one to five years. 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 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 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 loss. The functional currency of our Mexico operations is considered to be the United States dollar. Other Comprehensive Income (Loss) Other comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive net income (loss) consists of net income (loss), 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. See Note 15 Accumulated Other Comprehensive Loss (“AOCL”). All components are shown net of tax. Recent Accounting Pronouncements In June 2011, the Financial Accounting Standards Board issued Accounting Standards Update No. 2011-05, “Comprehensive Income (ASC Topic 220): Presentation of Comprehensive Income,” (“ASU 2011-05”) which amended prior comprehensive income guidance. ASU 2011-05 became effective for public companies during the interim and annual periods beginning after December 15, 2011 with early adoption permitted. Accordingly, the Company adopted this new standard on January 1, 2012 by including the consolidated statement of comprehensive income with its consolidated financial statements and revising Note 15 Accumulated Other Comprehensive Loss. The adoption of ASU 2011-05 did not have an impact on the Company’s consolidated financial position, results of operations or cash flows as it only requires a change in reporting format with regard to components of other comprehensive income. In February 2013, the Financial Accounting Standards Board issued Accounting Standards Update No. 2013-02, "Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Income," ("ASU 2013-02") which amended prior reporting requirements with respect to comprehensive income by requiring additional disclosures about the amounts reclassified out of accumulated other comprehensive loss by component. ASU 2013-02 became effective for public companies during interim and annual reporting periods beginning after December 15, 2012 with early adoption permitted. Accordingly, the Company adopted this new standard on January 1, 2013. The adoption of ASU 2013-02 did not have an impact on the Company's consolidated financial position, results of operations, or cash flows. 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 and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Reclassifications Certain prior year balances have been reclassified in the Consolidated Balance Sheets and Consolidated Statements of Cash Flows to conform to the 2012 presentation.

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 majority-owned subsidiary, TRIP Rail Holdings LLC ("TRIP Holdings"). All significant intercompany accounts and transactions have been eliminated. Certain amounts previously reported have been adjusted in the accompanying consolidated financial statements to remove the effects of discontinued operations. See Note 2 Acquisitions and Divestitures.

Stockholders' Equity

In September 2012, the Company’s Board of Directors authorized a new $200 million share repurchase program, effective October 1, 2012, which expires on December 31, 2014. The new program replaced the prior program which expired on September 30, 2012. During the year ended December 31, 2012, the Company repurchased 1,834,221 shares under the prior program at a cost of $45.2 million.

In 2011, an amount of $15.5 million was reclassified between capital in excess of par value and accumulated other comprehensive loss to properly reflect the additional amount of accumulated unrealized loss on derivative financial instruments attributable to the Company after the purchase of additional interests in TRIP Holdings.

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 pre-delivery acceptance on these contracts. This occurs primarily in the Rail and Inland Barge Groups. Revenue from rentals and operating leases, including contracts which 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 by the lease fleet for one year or less at the time of sale. Sales of railcars from the lease fleet that have been owned by the lease fleet 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.

Financial instruments that potentially subject the Company to a concentration of credit risk are primarily cash investments, 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 collectability of all receivables. Receivable balances determined to be uncollectible are charged against the allowance. The carrying values of cash, receivables and accounts payable are considered to be representative of their respective fair values. At December 31, 2012, one customer’s net receivable balance in our Energy Equipment Group, all within terms, 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 while renewals and major replacements are capitalized.

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 for the estimated cost to dispose of the assets. Impairment losses were not material for the years ended December 31, 2012, 2011, and 2010.

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 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. Step two of the impairment test is necessary to determine 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 related to revenue and operating profit growth, discount rates and exit multiples. As of December 31, 2012 and 2011, the Company's annual impairment test of goodwill was completed at the reporting unit level and no impairment charges were determined to be necessary.

Intangible assets with defined useful lives, which as of December 31, 2012 had net book values of $21.7 million, are amortized over their estimated useful lives, and were also evaluated for potential impairment as of December 31, 2012.

Restricted Cash

Restricted cash consists of cash and cash equivalents that are held as collateral for the Company's non-recourse debt and lease obligations and as such are restricted in use.

Insurance

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

Warranties

Depending on the product, the Company provides warranties against materials and manufacturing defects generally ranging from one to five years. 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 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

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 loss. The functional currency of our Mexico operations is considered to be the United States dollar.

Other Comprehensive Income (Loss)

Other comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive net income (loss) consists of net income (loss), 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. See Note 15 Accumulated Other Comprehensive Loss (“AOCL”). All components are shown net of tax.

Recent Accounting Pronouncements

In June 2011, the Financial Accounting Standards Board issued Accounting Standards Update No. 2011-05, “Comprehensive Income (ASC Topic 220): Presentation of Comprehensive Income,” (“ASU 2011-05”) which amended prior comprehensive income guidance. ASU 2011-05 became effective for public companies during the interim and annual periods beginning after December 15, 2011 with early adoption permitted. Accordingly, the Company adopted this new standard on January 1, 2012 by including the consolidated statement of comprehensive income with its consolidated financial statements and revising Note 15 Accumulated Other Comprehensive Loss. The adoption of ASU 2011-05 did not have an impact on the Company’s consolidated financial position, results of operations or cash flows as it only requires a change in reporting format with regard to components of other comprehensive income.

In February 2013, the Financial Accounting Standards Board issued Accounting Standards Update No. 2013-02, "Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Income," ("ASU 2013-02") which amended prior reporting requirements with respect to comprehensive income by requiring additional disclosures about the amounts reclassified out of accumulated other comprehensive loss by component. ASU 2013-02 became effective for public companies during interim and annual reporting periods beginning after December 15, 2012 with early adoption permitted. Accordingly, the Company adopted this new standard on January 1, 2013. The adoption of ASU 2013-02 did not have an impact on the Company's consolidated financial position, results of operations, or cash flows.

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 and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Reclassifications

Certain prior year balances have been reclassified in the Consolidated Balance Sheets and Consolidated Statements of Cash Flows to conform to the 2012 presentation.