Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues [Abstract]
Revenues	$ 371.5	$ 509.2	$ 770.3	$ 1,124.4
Cost of revenues:
Cost of revenues:	259.2	396.6	555.2	878.6
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	57.7	56.8	112.1	121.1
Gains on dispositions of property:
Lease portfolio sales (Note 1)	11.1	5.7	12.8	14.4
Other	1.0	0.9	10.8	1.8
Gains on dispositions of property:	12.1	6.6	23.6	16.2
Impairment of long-lived assets	0.0	369.4	0.0	369.4
Restructuring activities, net	(0.7)	0.3	(1.0)	5.8
Total operating profit (loss)	67.4	(307.3)	127.6	(234.3)
Other (income) expense:
Interest expense, net	51.0	53.0	102.3	106.9
Loss on extinguishment of debt	11.7	0.0	11.7	5.0
Other Nonoperating Expense	0.8		2.0
Other Nonoperating Income		0.7		1.5
Other (income) expense:	63.5	52.3	116.0	110.4
Income (loss) from continuing operations before income taxes	3.9	(359.6)	11.6	(344.7)
Current Income Tax Expense (Benefit)	0.5	(79.7)	5.3	(452.5)
Provision for deferred income taxes	(1.4)	7.9	(0.2)	233.1
Provision (benefit) for income taxes	(0.9)	(71.8)	5.1	(219.4)
Income (loss) from continuing operations	4.8	(287.8)	6.5	(125.3)
Loss from discontinued operations, net of provision (benefit) for income taxes of $—, $—, $0.4, and $(0.1)	0.0	0.0	(0.4)	(0.2)
Net income (loss)	4.8	(287.8)	6.1	(125.5)
Net loss attributable to noncontrolling interest	(7.9)	(80.9)	(9.9)	(80.3)
Net income (loss) attributable to Trinity Industries, Inc.	$ 12.7	$ (206.9)	$ 16.0	$ (45.2)
Basic earnings per common share:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.12	$ (1.76)	$ 0.15	$ (0.38)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0	0	0
Basic net income (loss) attributable to Trinity Industries, Inc.	0.12	(1.76)	0.15	(0.38)
Income (Loss) from Continuing Operations, Per Diluted Share	0.12	(1.76)	0.15	(0.38)
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0	0	0
Diluted net income (loss) attributable to Trinity Industries, Inc.	$ 0.12	$ (1.76)	$ 0.15	$ (0.38)
Weighted average number of shares outstanding:
Weighted Average Number of Shares Outstanding, Basic	102.8	117.3	106.4	117.6
Weighted Average Number of Shares Outstanding, Diluted	105.1	117.3	108.9	117.6
Manufacturing
Revenues [Abstract]
Revenues	$ 186.5	$ 316.6	$ 402.0	$ 695.7
Cost of revenues:
Cost of revenues:	156.7	293.7	356.0	637.1
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	17.4	19.6	37.8	41.5
Leasing
Revenues [Abstract]
Revenues	185.0	192.6	368.3	428.7
Cost of revenues:
Cost of revenues:	102.5	102.9	199.2	241.5
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	13.2	13.0	24.5	27.3
Other
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	$ 27.1	$ 24.2	$ 49.8	$ 52.3