Financial Statements for Guarantors of the Senior Notes - Statement of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Income Statements, Captions [Line Items]
Revenues	$ 736.0		$ 634.0		$ 1,340.8	$ 1,167.2
Cost of revenues	578.5		481.9		1,041.9	881.8
Selling, engineering, and administrative expenses	69.8		75.6		129.4	149.0
Gains on dispositions of property	19.3		11.5		29.3	13.7
Cost of revenues and operating costs	629.0		546.0		1,142.0	1,017.1
Total operating profit	107.0		88.0		198.8	150.1
Other Nonoperating Expense	55.3		38.2		107.0	79.4
Equity in earnings of subsidiaries, net of taxes	0.0		0.0		0.0	0.0
Income before income taxes	51.7		49.8		91.8	70.7
Provision (benefit) for income taxes	14.1		12.5		23.0	18.2
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	37.6		37.3		68.8	52.5
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.8)		28.2		(1.9)	54.6
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	36.8	$ 30.1	65.5	$ 41.6	66.9	107.1
Net Income (Loss) Attributable to Noncontrolling Interest	0.4		1.4		(0.1)	2.8
Net Income (Loss) Attributable to Parent	36.4		64.1		67.0	104.3
Other Comprehensive Income (Loss), Net of Tax	(6.2)	$ (3.8)	(0.5)	$ 1.9	(10.0)	1.4
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	30.6		65.0		56.9	108.5
Comprehensive income attributable to noncontrolling interest	0.7		1.8		0.5	3.6
Comprehensive income attributable to Trinity Industries, Inc.	29.9		63.2		56.4	104.9
Reportable legal entities | Parent
Condensed Income Statements, Captions [Line Items]
Revenues	0.0		0.0		0.0	0.0
Cost of revenues	0.3		0.5		1.2	0.7
Selling, engineering, and administrative expenses	26.6		38.2		47.3	74.3
Gains on dispositions of property	0.0		1.3		0.0	1.4
Cost of revenues and operating costs	26.9		37.4		48.5	73.6
Total operating profit	(26.9)		(37.4)		(48.5)	(73.6)
Other (income) expense	(4.1)		(0.3)		0.6	2.5
Equity in earnings of subsidiaries, net of taxes	65.6		102.6		119.8	183.9
Income before income taxes	42.8		65.5		70.7	107.8
Provision (benefit) for income taxes	5.7		(1.7)		2.1	(1.0)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	37.1		67.2		68.6	108.8
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.7)		(3.1)		(1.6)	(4.5)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	36.4		64.1		67.0	104.3
Net Income (Loss) Attributable to Noncontrolling Interest	0.0		0.0		0.0	0.0
Net Income (Loss) Attributable to Parent	36.4		64.1		67.0	104.3
Other Comprehensive Income (Loss), Net of Tax	0.8		0.3		1.6	0.4
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	37.2		64.4		68.6	104.7
Comprehensive income attributable to noncontrolling interest	0.0		0.0		0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	37.2		64.4		68.6	104.7
Reportable legal entities | Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	516.9		465.0		926.4	839.6
Cost of revenues	435.8		384.2		779.3	689.5
Selling, engineering, and administrative expenses	27.2		27.4		53.4	55.7
Gains on dispositions of property	7.4		13.8		9.1	15.7
Cost of revenues and operating costs	455.6		397.8		823.6	729.5
Total operating profit	61.3		67.2		102.8	110.1
Other (income) expense	8.3		7.8		9.8	15.8
Equity in earnings of subsidiaries, net of taxes	10.6		13.4		26.0	27.2
Income before income taxes	63.6		72.8		119.0	121.5
Provision (benefit) for income taxes	12.7		16.7		25.4	25.0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	50.9		56.1		93.6	96.5
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	50.9		56.1		93.6	96.5
Net Income (Loss) Attributable to Noncontrolling Interest	0.0		0.0		0.0	0.0
Net Income (Loss) Attributable to Parent	50.9		56.1		93.6	96.5
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	50.9		56.1		93.6	96.5
Comprehensive income attributable to noncontrolling interest	0.0		0.0		0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	50.9		56.1		93.6	96.5
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	280.8		224.5		541.8	460.9
Cost of revenues	215.6		159.3		409.6	337.8
Selling, engineering, and administrative expenses	16.0		10.0		28.7	19.0
Gains on dispositions of property	11.9		(3.6)		20.2	(3.4)
Cost of revenues and operating costs	219.7		172.9		418.1	360.2
Total operating profit	61.1		51.6		123.7	100.7
Other (income) expense	51.1		30.7		96.6	61.1
Equity in earnings of subsidiaries, net of taxes	6.6		7.6		11.6	12.9
Income before income taxes	16.6		28.5		38.7	52.5
Provision (benefit) for income taxes	1.1		2.9		2.3	4.2
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	15.5		25.6		36.4	48.3
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.1)		31.3		(0.3)	59.1
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	15.4		56.9		36.1	107.4
Net Income (Loss) Attributable to Noncontrolling Interest	0.0		0.0		0.0	0.0
Net Income (Loss) Attributable to Parent	15.4		56.9		36.1	107.4
Other Comprehensive Income (Loss), Net of Tax	(7.0)		(0.8)		(11.6)	1.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	8.4		56.1		24.5	108.4
Comprehensive income attributable to noncontrolling interest	0.0		0.0		0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	8.4		56.1		24.5	108.4
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	(61.7)		(55.5)		(127.4)	(133.3)
Cost of revenues	(73.2)		(62.1)		(148.2)	(146.2)
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	(73.2)		(62.1)		(148.2)	(146.2)
Total operating profit	11.5		6.6		20.8	12.9
Other (income) expense	0.0		0.0		0.0	0.0
Equity in earnings of subsidiaries, net of taxes	(82.8)		(123.6)		(157.4)	(224.0)
Income before income taxes	(71.3)		(117.0)		(136.6)	(211.1)
Provision (benefit) for income taxes	(5.4)		(5.4)		(6.8)	(10.0)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(65.9)		(111.6)		(129.8)	(201.1)
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	(65.9)		(111.6)		(129.8)	(201.1)
Net Income (Loss) Attributable to Noncontrolling Interest	0.4		1.4		(0.1)	2.8
Net Income (Loss) Attributable to Parent	(66.3)		(113.0)		(129.7)	(203.9)
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	(65.9)		(111.6)		(129.8)	(201.1)
Comprehensive income attributable to noncontrolling interest	0.7		1.8		0.5	3.6
Comprehensive income attributable to Trinity Industries, Inc.	$ (66.6)		$ (113.4)		$ (130.3)	$ (204.7)