Consolidated Statements of Operations - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:	$ 1,999,400,000	$ 3,005,100,000	$ 2,509,100,000
Cost of revenues:	1,508,400,000	2,365,700,000	1,938,800,000
Selling, engineering, and administrative expenses:	228,400,000	262,800,000	296,600,000
Net gains on railcar lease fleet sales owned more than one year at the time of sale	17,300,000	50,500,000	50,400,000
Gain (Loss) on Disposition of Other Assets	3,000,000.0	3,900,000	(9,000,000.0)
Gains (losses) on dispositions of property:	20,300,000	54,400,000	41,400,000
Impairment of long-lived assets	396,400,000	0	0
Restructuring activities, net	11,000,000.0	14,700,000	0
Total operating profit (loss)	(124,500,000)	416,300,000	315,100,000
Interest income	(3,200,000)	(7,300,000)	(11,900,000)
Interest expense	219,200,000	221,800,000	179,300,000
Pension plan settlement	(151,500,000)	0	0
Other Nonoperating Income			(3,900,000)
Other Nonoperating Expense	2,500,000	1,100,000
Other (income) expense:	370,000,000.0	215,600,000	163,500,000
Income (loss) from continuing operations before income taxes	(494,500,000)	200,700,000	151,600,000
Current Income Tax Expense (Benefit)	(494,500,000)	6,700,000	(15,300,000)
Provision for deferred income taxes	226,100,000	54,800,000	57,900,000
Provision (benefit) for income taxes:	(268,400,000)	61,500,000	42,600,000
Income (loss) from continuing operations	(226,100,000)	139,200,000	109,000,000.0
Income (loss) from discontinued operations, net of provision (benefit) for income taxes of $(0.1), $(1.0), $30.7	(100,000)	(3,100,000)	54,100,000
Net income (loss)	(226,200,000)	136,100,000	163,100,000
Net income (loss) attributable to noncontrolling interest	(78,900,000)	(1,500,000)	3,800,000
Net income (loss) attributable to Trinity Industries, Inc.	$ (147,300,000)	$ 137,600,000	$ 159,300,000
Income (loss) from continuing operations	$ (1.27)	$ 1.11	$ 0.72
Income (loss) from discontinued operations	0	(0.02)	0.37
Basic net income (loss) attributable to Trinity Industries, Inc.	(1.27)	1.09	1.09
Income (loss) from continuing operations	(1.27)	1.09	0.70
Income (loss) from discontinued operations	0	(0.02)	0.37
Diluted net income (loss) attributable to Trinity Industries, Inc.	$ (1.27)	$ 1.07	$ 1.07
Basic weighted average shares outstanding	115.9	125.6	144.0
Diluted weighted average shares outstanding	115.9	127.3	146.4
Manufacturing [Member]
Revenues:	$ 1,197,700,000	$ 1,888,800,000	$ 1,667,100,000
Cost of revenues:	1,091,000,000.0	1,649,500,000	1,459,800,000
Selling, engineering, and administrative expenses:	79,400,000	105,300,000	96,400,000
Leasing [Member]
Revenues:	801,700,000	1,116,300,000	842,000,000.0
Cost of revenues:	417,400,000	716,200,000	479,000,000.0
Selling, engineering, and administrative expenses:	51,300,000	49,500,000	51,100,000
Other [Member]
Selling, engineering, and administrative expenses:	$ 97,700,000	$ 108,000,000.0	$ 149,100,000