Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The foregoing consolidated financial statements are unaudited and have been prepared from the books and records of Trinity Industries, Inc. and its consolidated subsidiaries (“Trinity”, “Company”, “we”, or “our”) including 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. In our opinion, all normal and recurring adjustments necessary for a fair presentation of the financial position of the Company as of June 30, 2015, and the results of operations for the three and six months ended June 30, 2015 and 2014, and cash flows for the six months ended June 30, 2015 and 2014, have been made in conformity with generally accepted accounting principles. All significant intercompany accounts and transactions have been eliminated. Because of seasonal and other factors, the results of operations for the six months ended June 30, 2015 may not be indicative of expected results of operations for the year ending December 31, 2015. These interim financial statements and notes are condensed as permitted by the instructions to Form 10-Q and should be read in conjunction with the audited consolidated financial statements of the Company included in its Form 10-K for the year ended December 31, 2014.
Stockholders' Equity	Stockholders' Equity In March 2014, the Company’s Board of Directors authorized a $250 million share repurchase program that expires on December 31, 2015. Under the program, 1,669,764 shares and 2,390,804 shares, respectively, were repurchased during the three and six months ended June 30, 2015, at a cost of approximately $50.0 million and $75.0 million, respectively. During the three and six months ended June 30, 2014, the Company repurchased 63,600 shares and 340,146 shares, respectively, at a cost of approximately $2.5 million and $12.5 million, respectively. 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	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. 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 for one year or less at the time of sale. Sales of railcars from the lease fleet that have been 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.
Financial Instruments	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, receivables, and accounts payable are considered to be representative of their respective fair values. At June 30, 2015, one customer's net receivable balance in our Rail Group accounted for 11% of the consolidated net receivables balance outstanding.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2015-03, "Simplifying the Presentation of Debt Issuance Costs" ("ASU 2015-03") which changes the presentation of debt issuance costs in financial statements to present such costs as a direct deduction from the related debt liability rather than as an asset. ASU 2015-03 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted. We do not expect the adoption of ASU 2015-03 will have a material impact on our consolidated financial statements. In February 2015, the FASB issued Accounting Standards Update No. 2015-02, "Consolidation (Topic 810): Amendments to the Consolidation Analysis" ("ASU 2015-02") which updates the considerations on whether an entity should consolidate certain legal entities. The update removes the indefinite deferral of specialized guidance for certain investment funds and changes the way that entities evaluate limited partnerships and fees paid to service providers in the consolidation determination. ASU 2015-02 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted. We do not expect the adoption of ASU 2015-02 will have a material impact on our consolidated financial statements. In May 2014, the 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. We are currently evaluating the impact this standard will have on our consolidated financial statements.
Reclassifications	Reclassifications Certain prior year balances have been reclassified in the consolidated statements of operations and cash flows to conform to the 2015 presentation.

Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.