Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues [Abstract]
Revenues	$ 398.8	$ 615.2
Cost of revenues:
Cost of revenues:	296.0	482.0
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	54.4	64.3
Gains on dispositions of property:
Lease portfolio sales (Note 1)	1.7	8.7
Other	9.8	0.9
Gains on dispositions of property:	11.5	9.6
Restructuring activities, net	(0.3)	5.5
Total operating profit	60.2	73.0
Other (income) expense:
Interest income	(0.1)	(2.4)
Interest expense	51.4	61.3
Other Nonoperating Expense	1.2
Other Nonoperating Income		0.8
Other (income) expense:	(52.5)	(58.1)
Income from continuing operations before income taxes	7.7	14.9
Current Income Tax Expense (Benefit)	4.8	(372.8)
Provision for deferred income taxes	1.2	225.2
Provision (benefit) for income taxes	6.0	(147.6)
Income from continuing operations	1.7	162.5
Loss from discontinued operations, net of provision (benefit) for income taxes of $0.4 and $(0.1)	(0.4)	(0.2)
Net income	1.3	162.3
Net income (loss) attributable to noncontrolling interest	(2.0)	0.6
Net income attributable to Trinity Industries, Inc.	$ 3.3	$ 161.7
Basic earnings per common share:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.03	$ 1.36
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0
Basic net income attributable to Trinity Industries, Inc.	0.03	1.36
Income (Loss) from Continuing Operations, Per Diluted Share	0.03	1.33
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0
Diluted net income attributable to Trinity Industries, Inc.	$ 0.03	$ 1.33
Weighted average number of shares outstanding:
Weighted Average Number of Shares Outstanding, Basic	110.2	118.0
Weighted Average Number of Shares Outstanding, Diluted	112.6	119.9
Manufacturing
Revenues [Abstract]
Revenues	$ 215.5	$ 379.1
Cost of revenues:
Cost of revenues:	199.3	343.4
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	20.4	21.9
Leasing
Revenues [Abstract]
Revenues	183.3	236.1
Cost of revenues:
Cost of revenues:	96.7	138.6
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	11.3	14.3
Other
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	$ 22.7	$ 28.1