Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues [Abstract]
Revenues	$ 503.5	$ 459.4	$ 1,273.8	$ 1,583.8
Cost of revenues:
Cost of revenues:	398.7	334.5	953.9	1,213.1
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	54.3	51.2	166.4	172.3
Gains on dispositions of property:
Lease portfolio sales (Note 1)	32.9	2.9	45.7	17.3
Other	8.7	1.0	19.5	2.8
Gains on dispositions of property:	41.6	3.9	65.2	20.1
Impairment of long-lived assets	0.0	0.0	0.0	369.4
Restructuring activities, net	(0.1)	4.7	(1.1)	10.5
Total operating profit (loss)	92.2	72.9	219.8	(161.4)
Other (income) expense:
Interest expense, net	45.2	51.7	147.5	158.6
Loss on extinguishment of debt	0.0	0.0	11.7	5.0
Other Nonoperating Income	(0.7)	2.0	1.3	0.5
Other (income) expense:	44.5	53.7	160.5	164.1
Income (loss) from continuing operations before income taxes	47.7	19.2	59.3	(325.5)
Current Income Tax Expense (Benefit)	0.6	(18.7)	5.9	(471.2)
Provision for deferred income taxes	10.8	12.0	10.6	245.1
Provision (benefit) for income taxes	11.4	(6.7)	16.5	(226.1)
Income (loss) from continuing operations	36.3	25.9	42.8	(99.4)
Loss from discontinued operations, net of provision (benefit) for income taxes of $0.4, $—, $0.8, and $(0.1)	(0.4)	0.0	(0.8)	(0.2)
Net income (loss)	35.9	25.9	42.0	(99.6)
Net income (loss) attributable to noncontrolling interest	3.9	0.8	(6.0)	(79.5)
Net income (loss) attributable to Trinity Industries, Inc.	$ 32.0	$ 25.1	$ 48.0	$ (20.1)
Basic earnings per common share:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.33	$ 0.21	$ 0.47	$ (0.17)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0	(0.01)	0
Basic net income (loss) attributable to Trinity Industries, Inc.	0.33	0.21	0.46	(0.17)
Income (Loss) from Continuing Operations, Per Diluted Share	0.33	0.21	0.46	(0.17)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0	(0.01)	0
Diluted net income (loss) attributable to Trinity Industries, Inc.	$ 0.33	$ 0.21	$ 0.45	$ (0.17)
Weighted average number of shares outstanding:
Weighted Average Number of Shares Outstanding, Basic	97.7	116.4	103.4	117.2
Weighted Average Number of Shares Outstanding, Diluted	99.5	117.0	105.7	117.2
Manufacturing
Revenues [Abstract]
Revenues	$ 318.2	$ 275.7	$ 720.2	$ 971.4
Cost of revenues:
Cost of revenues:	300.1	248.1	656.1	885.2
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	18.8	18.5	56.6	60.0
Leasing
Revenues [Abstract]
Revenues	185.3	183.7	553.6	612.4
Cost of revenues:
Cost of revenues:	98.6	86.4	297.8	327.9
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	11.6	11.7	36.1	39.0
Other
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	$ 23.9	$ 21.0	$ 73.7	$ 73.3