Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies 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, 2016, and the results of operations for the three and six months ended June 30, 2016 and 2015, and cash flows for the six months ended June 30, 2016 and 2015, 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, 2016 may not be indicative of expected results of operations for the year ending December 31, 2016. 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, 2015. 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. 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 six months ended June 30, 2016, at a cost of approximately $34.7 million. There were no shares repurchased during the three months ended June 30, 2016. During the three and six months ended June 30, 2015, the Company repurchased 1,669,764 shares and 2,390,804 shares, respectively, at a cost of approximately $50.0 million and $75.0 million, respectively. 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 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 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 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 June 30, 2016, one customer's net receivable balance in our Rail Group accounted for 11% of the consolidated net receivables balance outstanding. 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. We are currently evaluating the impact this standard will have on our consolidated financial statements. 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. We are currently evaluating the impact this standard will have on our consolidated financial statements. 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 will change 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 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2016 with early adoption permitted. 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.

Summary of Significant Accounting Policies

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, 2016, and the results of operations for the three and six months ended June 30, 2016 and 2015, and cash flows for the six months ended June 30, 2016 and 2015, 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, 2016 may not be indicative of expected results of operations for the year ending December 31, 2016. 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, 2015.

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. 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 six months ended June 30, 2016, at a cost of approximately $34.7 million. There were no shares repurchased during the three months ended June 30, 2016. During the three and six months ended June 30, 2015, the Company repurchased 1,669,764 shares and 2,390,804 shares, respectively, at a cost of approximately $50.0 million and $75.0 million, respectively.

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 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 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

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 June 30, 2016, one customer's net receivable balance in our Rail Group accounted for 11% of the consolidated net receivables balance outstanding.

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. We are currently evaluating the impact this standard will have on our consolidated financial statements.

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. We are currently evaluating the impact this standard will have on our consolidated financial statements.

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 will change 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 will become effective for public companies during interim and annual reporting periods beginning after December 15, 2016 with early adoption permitted. 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.