Financial Statements for Guarantors of the Senior Notes - Statement of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Income Statements, Captions [Line Items]
Revenues	$ 930.9	$ 973.6	$ 2,704.5	$ 2,756.4
Cost of revenues	752.0	722.7	2,100.2	2,065.2
Selling, engineering, and administrative expenses	111.1	114.6	326.4	330.1
Gains on dispositions of property	11.1	16.1	25.1	41.8
Cost of revenues and operating costs	852.0	821.2	2,401.5	2,353.5
Total operating profit	78.9	152.4	303.0	402.9
Other (income) expense	39.9	44.8	121.5	131.5
Equity in earnings of subsidiaries, net of taxes	0.0	0.0	0.0	0.0
Income before income taxes	39.0	107.6	181.5	271.4
Provision (benefit) for income taxes	10.7	39.7	46.1	97.8
Net income	28.3	67.9	135.4	173.6
Net income attributable to noncontrolling interest	0.6	1.0	3.4	9.6
Net income attributable to Trinity Industries, Inc.	27.7	66.9	132.0	164.0
Other comprehensive income (loss)	2.1	2.1	3.5	6.4
Comprehensive income	30.4	70.0	138.9	180.0
Comprehensive income attributable to noncontrolling interest	0.9	1.5	4.5	11.6
Comprehensive income attributable to Trinity Industries, Inc.	29.5	68.5	134.4	168.4
Reportable legal entities | Parent
Condensed Income Statements, Captions [Line Items]
Revenues	0.0	0.0	0.0	0.0
Cost of revenues	5.7	(0.1)	6.4	3.7
Selling, engineering, and administrative expenses	40.0	39.5	119.3	108.4
Gains on dispositions of property	(0.1)	(0.1)	1.3	0.5
Cost of revenues and operating costs	45.8	39.5	124.4	111.6
Total operating profit	(45.8)	(39.5)	(124.4)	(111.6)
Other (income) expense	(4.3)	5.7	(2.5)	16.9
Equity in earnings of subsidiaries, net of taxes	62.8	111.7	244.3	274.1
Income before income taxes	21.3	66.5	122.4	145.6
Provision (benefit) for income taxes	(6.4)	(0.4)	(9.6)	(18.4)
Net income	27.7	66.9	132.0	164.0
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Trinity Industries, Inc.	27.7	66.9	132.0	164.0
Other comprehensive income (loss)	1.4	1.8	1.8	4.1
Comprehensive income	29.1	68.7	133.8	168.1
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	29.1	68.7	133.8	168.1
Reportable legal entities | Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	526.2	622.5	1,558.5	1,738.6
Cost of revenues	442.3	493.6	1,292.3	1,393.1
Selling, engineering, and administrative expenses	32.4	35.6	99.8	100.3
Gains on dispositions of property	7.7	15.9	17.1	36.9
Cost of revenues and operating costs	467.0	513.3	1,375.0	1,456.5
Total operating profit	59.2	109.2	183.5	282.1
Other (income) expense	8.3	6.1	24.2	21.3
Equity in earnings of subsidiaries, net of taxes	16.4	17.5	63.3	60.6
Income before income taxes	67.3	120.6	222.6	321.4
Provision (benefit) for income taxes	9.9	35.5	37.3	105.8
Net income	57.4	85.1	185.3	215.6
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Trinity Industries, Inc.	57.4	85.1	185.3	215.6
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income	57.4	85.1	185.3	215.6
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	57.4	85.1	185.3	215.6
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	550.3	501.3	1,585.4	1,438.5
Cost of revenues	455.1	385.7	1,260.3	1,107.0
Selling, engineering, and administrative expenses	38.7	39.5	107.3	121.4
Gains on dispositions of property	3.5	0.3	6.7	4.4
Cost of revenues and operating costs	490.3	424.9	1,360.9	1,224.0
Total operating profit	60.0	76.4	224.5	214.5
Other (income) expense	35.9	33.0	99.8	93.3
Equity in earnings of subsidiaries, net of taxes	0.0	0.0	0.0	0.0
Income before income taxes	24.1	43.4	124.7	121.2
Provision (benefit) for income taxes	6.9	6.4	27.7	26.0
Net income	17.2	37.0	97.0	95.2
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Trinity Industries, Inc.	17.2	37.0	97.0	95.2
Other comprehensive income (loss)	0.7	0.3	1.7	2.3
Comprehensive income	17.9	37.3	98.7	97.5
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	17.9	37.3	98.7	97.5
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	(145.6)	(150.2)	(439.4)	(420.7)
Cost of revenues	(151.1)	(156.5)	(458.8)	(438.6)
Selling, engineering, and administrative expenses	0.0	0.0	0.0	0.0
Gains on dispositions of property	0.0	0.0	0.0	0.0
Cost of revenues and operating costs	(151.1)	(156.5)	(458.8)	(438.6)
Total operating profit	5.5	6.3	19.4	17.9
Other (income) expense	0.0	0.0	0.0	0.0
Equity in earnings of subsidiaries, net of taxes	(79.2)	(129.2)	(307.6)	(334.7)
Income before income taxes	(73.7)	(122.9)	(288.2)	(316.8)
Provision (benefit) for income taxes	0.3	(1.8)	(9.3)	(15.6)
Net income	(74.0)	(121.1)	(278.9)	(301.2)
Net income attributable to noncontrolling interest	0.6	1.0	3.4	9.6
Net income attributable to Trinity Industries, Inc.	(74.6)	(122.1)	(282.3)	(310.8)
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income	(74.0)	(121.1)	(278.9)	(301.2)
Comprehensive income attributable to noncontrolling interest	0.9	1.5	4.5	11.6
Comprehensive income attributable to Trinity Industries, Inc.	$ (74.9)	$ (122.6)	$ (283.4)	$ (312.8)