Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues [Abstract]
Revenues	$ 459.4	$ 813.6	$ 1,583.8	$ 2,154.4
Cost of revenues:
Cost of revenues:	334.5	649.1	1,213.1	1,691.0
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	51.2	62.1	172.3	191.5
Gains (losses) on dispositions of property:
Net gains on railcar lease fleet sales owned more than one year at the time of sale	2.9	18.1	17.3	44.7
Other	1.0	(0.2)	2.8	2.5
Gain (Loss) on Disposition of Property Plant Equipment	3.9	17.9	20.1	47.2
Impairment of long-lived assets	0.0	0.0	369.4	0.0
Restructuring activities, net	4.7	0.0	10.5	0.0
Operating profit on sales of leased railcars:	72.9	120.3	(161.4)	319.1
Other (income) expense:
Interest income	(0.6)	(1.8)	(3.0)	(4.7)
Interest expense	52.3	55.8	166.6	165.5
Other, net	2.0	0.0	0.5	0.2
Other (income) expense	53.7	54.0	164.1	161.0
Income (loss) from continuing operations before income taxes	19.2	66.3	(325.5)	158.1
Current Income Tax Expense (Benefit)	(18.7)	2.5	(471.2)	2.7
Provision for deferred income taxes	12.0	15.7	245.1	38.5
Provision (benefit) for income taxes	(6.7)	18.2	(226.1)	41.2
Income (loss) from continuing operations	25.9	48.1	(99.4)	116.9
Loss from discontinued operations, net of benefit for income taxes of $—, $0.1, $0.1, and $0.6	0.0	(0.4)	(0.2)	(2.3)
Discontinued Operation, Tax Effect of Discontinued Operation	0.0	(0.1)	(0.1)	(0.6)
Net income (loss)	25.9	47.7	(99.6)	114.6
Net income (loss) attributable to noncontrolling interest	0.8	(1.3)	(79.5)	(1.4)
Net income (loss) attributable to Trinity Industries, Inc.	$ 25.1	$ 49.0	$ (20.1)	$ 116.0
Basic earnings per common share:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.21	$ 0.39	$ (0.17)	$ 0.91
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0	0	(0.02)
Basic net income (loss) attributable to Trinity Industries, Inc.	0.21	0.39	(0.17)	0.89
Income (Loss) from Continuing Operations, Per Diluted Share	0.21	0.39	(0.17)	0.90
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0	0	(0.02)
Diluted net income (loss) attributable to Trinity Industries, Inc.	$ 0.21	$ 0.39	$ (0.17)	$ 0.88
Weighted average number of shares outstanding:
Weighted Average Number of Shares Outstanding, Basic	116.4	124.7	117.2	127.6
Weighted Average Number of Shares Outstanding, Diluted	117.0	126.0	117.2	129.2
Manufacturing
Revenues [Abstract]
Revenues	$ 275.7	$ 487.4	$ 971.4	$ 1,351.1
Cost of revenues:
Cost of revenues:	248.1	430.7	885.2	1,181.9
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	18.5	27.5	60.0	77.2
Leasing
Revenues [Abstract]
Revenues	183.7	326.2	612.4	803.3
Cost of revenues:
Cost of revenues:	86.4	218.4	327.9	509.1
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	11.7	10.7	39.0	36.2
Other
Selling, engineering, and administrative expenses:
Selling, engineering, and administrative expenses:	$ 21.0	$ 23.9	$ 73.3	$ 78.1