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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Income Statements, Captions [Line Items]
Revenues	$ 813.6			$ 606.9			$ 2,154.4	$ 1,774.1
Cost of revenues	649.1			466.5			1,691.0	1,348.3
Selling, engineering, and administrative expenses	62.1			75.6			191.5	224.6
Gains on dispositions of property	17.9			10.4			47.2	24.1
Cost of revenues and operating costs	693.3			531.7			1,835.3	1,548.8
Total operating profit	120.3			75.2			319.1	225.3
Other Nonoperating Expense	54.0			40.0			161.0	119.4
Equity in earnings of subsidiaries, net of taxes	0.0			0.0			0.0	0.0
Income before income taxes	66.3			35.2			158.1	105.9
Provision (benefit) for income taxes	18.2			6.7			41.2	24.9
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	48.1			28.5			116.9	81.0
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.4)			(0.2)			(2.3)	54.4
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	47.7	$ 36.8	$ 30.1	28.3	$ 65.5	$ 41.6	114.6	135.4
Net Income (Loss) Attributable to Noncontrolling Interest	(1.3)			0.6			(1.4)	3.4
Net Income (Loss) Attributable to Parent	49.0			27.7			116.0	132.0
Other Comprehensive Income (Loss), Net of Tax	(2.7)	$ (6.2)	$ (3.8)	2.1	$ (0.5)	$ 1.9	(12.7)	3.5
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	45.0			30.4			101.9	138.9
Comprehensive income attributable to noncontrolling interest	(0.9)			0.9			(0.4)	4.5
Comprehensive income attributable to Trinity Industries, Inc.	45.9			29.5			102.3	134.4
Reportable legal entities | Parent
Condensed Income Statements, Captions [Line Items]
Revenues	0.0			0.0			0.0	0.0
Cost of revenues	1.1			1.6			2.3	2.3
Selling, engineering, and administrative expenses	24.0			35.6			71.3	109.9
Gains on dispositions of property	(0.2)			0.0			(0.2)	1.4
Cost of revenues and operating costs	25.3			37.2			73.8	110.8
Total operating profit	(25.3)			(37.2)			(73.8)	(110.8)
Other (income) expense	(0.6)			(3.9)			0.0	(1.4)
Equity in earnings of subsidiaries, net of taxes	75.6			63.8			195.4	247.7
Income before income taxes	50.9			30.5			121.6	138.3
Provision (benefit) for income taxes	1.4			(5.3)			3.5	(6.3)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	49.5			35.8			118.1	144.6
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.5)			(8.1)			(2.1)	(12.6)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	49.0			27.7			116.0	132.0
Net Income (Loss) Attributable to Noncontrolling Interest	0.0			0.0			0.0	0.0
Net Income (Loss) Attributable to Parent	49.0			27.7			116.0	132.0
Other Comprehensive Income (Loss), Net of Tax	0.9			1.4			2.5	1.8
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	49.9			29.1			118.5	133.8
Comprehensive income attributable to noncontrolling interest	0.0			0.0			0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	49.9			29.1			118.5	133.8
Reportable legal entities | Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	566.3			449.0			1,492.7	1,288.6
Cost of revenues	466.8			375.2			1,246.1	1,059.1
Selling, engineering, and administrative expenses	24.2			28.3			77.6	84.0
Gains on dispositions of property	11.3			8.4			20.4	18.5
Cost of revenues and operating costs	479.7			395.1			1,303.3	1,124.6
Total operating profit	86.6			53.9			189.4	164.0
Other (income) expense	4.8			8.4			14.6	24.2
Equity in earnings of subsidiaries, net of taxes	6.0			8.0			32.0	35.2
Income before income taxes	87.8			53.5			206.8	175.0
Provision (benefit) for income taxes	21.5			8.4			46.9	33.4
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	66.3			45.1			159.9	141.6
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.0			0.0			0.0	0.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	66.3			45.1			159.9	141.6
Net Income (Loss) Attributable to Noncontrolling Interest	0.0			0.0			0.0	0.0
Net Income (Loss) Attributable to Parent	66.3			45.1			159.9	141.6
Other Comprehensive Income (Loss), Net of Tax	0.0			0.0			0.0	0.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	66.3			45.1			159.9	141.6
Comprehensive income attributable to noncontrolling interest	0.0			0.0			0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	66.3			45.1			159.9	141.6
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	311.3			231.5			853.1	692.4
Cost of revenues	254.7			171.9			664.3	515.3
Selling, engineering, and administrative expenses	13.9			11.7			42.6	30.7
Gains on dispositions of property	6.8			2.0			27.0	4.2
Cost of revenues and operating costs	261.8			181.6			679.9	541.8
Total operating profit	49.5			49.9			173.2	150.6
Other (income) expense	50.1			35.5			146.7	96.6
Equity in earnings of subsidiaries, net of taxes	8.1			7.3			19.7	20.2
Income before income taxes	7.5			21.7			46.2	74.2
Provision (benefit) for income taxes	1.0			2.4			3.3	6.6
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	6.5			19.3			42.9	67.6
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.1			7.9			(0.2)	67.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	6.6			27.2			42.7	134.6
Net Income (Loss) Attributable to Noncontrolling Interest	0.0			0.0			0.0	0.0
Net Income (Loss) Attributable to Parent	6.6			27.2			42.7	134.6
Other Comprehensive Income (Loss), Net of Tax	(3.6)			0.7			(15.2)	1.7
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	3.0			27.9			27.5	136.3
Comprehensive income attributable to noncontrolling interest	0.0			0.0			0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	3.0			27.9			27.5	136.3
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	(64.0)			(73.6)			(191.4)	(206.9)
Cost of revenues	(73.5)			(82.2)			(221.7)	(228.4)
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	(73.5)			(82.2)			(221.7)	(228.4)
Total operating profit	9.5			8.6			30.3	21.5
Other (income) expense	(0.3)			0.0			(0.3)	0.0
Equity in earnings of subsidiaries, net of taxes	(89.7)			(79.1)			(247.1)	(303.1)
Income before income taxes	(79.9)			(70.5)			(216.5)	(281.6)
Provision (benefit) for income taxes	(5.7)			1.2			(12.5)	(8.8)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(74.2)			(71.7)			(204.0)	(272.8)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.0			0.0			0.0	0.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(74.2)			(71.7)			(204.0)	(272.8)
Net Income (Loss) Attributable to Noncontrolling Interest	(1.3)			0.6			(1.4)	3.4
Net Income (Loss) Attributable to Parent	(72.9)			(72.3)			(202.6)	(276.2)
Other Comprehensive Income (Loss), Net of Tax	0.0			0.0			0.0	0.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(74.2)			(71.7)			(204.0)	(272.8)
Comprehensive income attributable to noncontrolling interest	(0.9)			0.9			(0.4)	4.5
Comprehensive income attributable to Trinity Industries, Inc.	$ (73.3)			$ (72.6)			$ (203.6)	$ (277.3)