Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2017
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 September 30, 2017, and the results of operations for the three and nine months ended September 30, 2017 and 2016, and cash flows for the nine months ended September 30, 2017 and 2016, 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 nine months ended September 30, 2017 may not be indicative of expected results of operations for the year ending December 31, 2017. 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, 2016.
Stockholders' Equity	Stockholders' Equity In December 2015, the Company’s Board of Directors renewed its $250 million share repurchase program effective January 1, 2016 through December 31, 2017. Under the program, 1,942,200 shares were repurchased during the nine months ended September 30, 2017, at a cost of approximately $52.4 million. There were no shares repurchased during the three months ended September 30, 2017. During the nine months ended September 30, 2016, the Company repurchased 2,070,600 shares at a cost of approximately $34.7 million. There were no shares repurchased during the three months ended September 30, 2016. As of September 30, 2017, the remaining authorization under the program totaled $163.0 million.
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. Revenues for certain customer-requested “bill and hold” arrangements, primarily in the Energy Equipment Group, are recognized when all of the following conditions have been met: the risks of ownership have passed to the customer, the customer has made a fixed commitment to purchase the goods, there is a fixed delivery schedule consistent with the customer’s business purpose, the customer’s goods have been segregated from our inventory and are not available to fill other orders, the goods are complete and ready for shipment, and no additional performance obligations exist for the Company. 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.
Cash and Cash Equivalents	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.
Concentration of Credit Risk	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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On January 1, 2017, the Company adopted Accounting Standards Update 2016-09, “Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting”, ("ASU 2016-09”) which changed how companies account for certain aspects of share-based payments to employees. ASU 2016-09 requires, among other things, that excess tax benefits or deficiencies related to vested awards, previously recognized in stockholders' equity, be included in income tax expense when the awards vest. The adoption of ASU 2016-09 resulted in an adjustment to retained earnings of $0.6 million, net of tax, as of January 1, 2017 related to the cumulative effect of the standard. For the three and nine months ended September 30, 2017, the effect on the provision for income taxes included in the consolidated statement of operations was a benefit of $0.2 million and an additional provision of $2.2 million, respectively. 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 has substantially completed its evaluation of the requirements of the standard and their application to our various business units. Accordingly, 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. Additionally, we do not anticipate significant changes in business processes or systems. The Company is developing additional internal controls over financial reporting to ensure that the requirements of the new standard are satisfied. 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 November 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. The effect of adopting this standard is not expected to be significant. In March 2017, the FASB issued Accounting Standards Update No. 2017-07, “Compensation - Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” (“ASU 2017-07”) which changes how companies that sponsor defined benefit pension plans present the related net periodic benefit cost in the income statement. The service cost component of the net periodic benefit cost will continue to be presented in the same income statement line items, however other components of the net periodic benefit cost will be presented as a component of other income and excluded from operating profit. ASU 2017-07 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 2017-07 effective January 1, 2018. The effect of adopting this standard is not expected to be significant.