Financial Statements for Guarantors of the Senior Notes - Statement of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Income Statements, Captions [Line Items]
Revenues	$ 604.8	$ 533.2
Cost of revenues	463.4	399.9
Selling, engineering, and administrative expenses	59.6	73.4
Gains on dispositions of property	10.0	2.2
Cost of revenues and operating costs	513.0	471.1
Total operating profit	91.8	62.1
Other Nonoperating Expense	51.7	41.2
Equity in earnings of subsidiaries, net of taxes	0.0	0.0
Income before income taxes	40.1	20.9
Provision (benefit) for income taxes	8.9	5.7
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	31.2	15.2
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(1.1)	26.4
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	30.1	41.6
Net Income (Loss) Attributable to Noncontrolling Interest	(0.5)	1.4
Net Income (Loss) Attributable to Parent	30.6	40.2
Other Comprehensive Income (Loss), Net of Tax	(3.8)	1.9
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	26.3	43.5
Comprehensive income attributable to noncontrolling interest	(0.3)	1.8
Comprehensive income attributable to Trinity Industries, Inc.	26.6	41.7
Reportable legal entities | Parent
Condensed Income Statements, Captions [Line Items]
Revenues	0.0	0.0
Cost of revenues	0.9	0.2
Selling, engineering, and administrative expenses	20.7	36.1
Gains on dispositions of property	0.0	0.1
Cost of revenues and operating costs	21.6	36.2
Total operating profit	(21.6)	(36.2)
Other (income) expense	4.7	2.8
Equity in earnings of subsidiaries, net of taxes	54.2	81.3
Income before income taxes	27.9	42.3
Provision (benefit) for income taxes	(3.6)	0.7
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	31.5	41.6
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.9)	(1.4)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	30.6	40.2
Net Income (Loss) Attributable to Noncontrolling Interest	0.0	0.0
Net Income (Loss) Attributable to Parent	30.6	40.2
Other Comprehensive Income (Loss), Net of Tax	0.8	0.1
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	31.4	40.3
Comprehensive income attributable to noncontrolling interest	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	31.4	40.3
Reportable legal entities | Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	409.5	374.6
Cost of revenues	343.5	305.3
Selling, engineering, and administrative expenses	26.2	28.3
Gains on dispositions of property	1.7	1.9
Cost of revenues and operating costs	368.0	331.7
Total operating profit	41.5	42.9
Other (income) expense	1.5	8.0
Equity in earnings of subsidiaries, net of taxes	15.4	13.8
Income before income taxes	55.4	48.7
Provision (benefit) for income taxes	12.7	8.3
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	42.7	40.4
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.0	0.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	42.7	40.4
Net Income (Loss) Attributable to Noncontrolling Interest	0.0	0.0
Net Income (Loss) Attributable to Parent	42.7	40.4
Other Comprehensive Income (Loss), Net of Tax	0.0	0.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	42.7	40.4
Comprehensive income attributable to noncontrolling interest	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	42.7	40.4
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	261.0	236.4
Cost of revenues	194.0	178.5
Selling, engineering, and administrative expenses	12.7	9.0
Gains on dispositions of property	8.3	0.2
Cost of revenues and operating costs	198.4	187.3
Total operating profit	62.6	49.1
Other (income) expense	45.5	30.4
Equity in earnings of subsidiaries, net of taxes	5.0	5.3
Income before income taxes	22.1	24.0
Provision (benefit) for income taxes	1.2	1.3
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	20.9	22.7
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.2)	27.8
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	20.7	50.5
Net Income (Loss) Attributable to Noncontrolling Interest	0.0	0.0
Net Income (Loss) Attributable to Parent	20.7	50.5
Other Comprehensive Income (Loss), Net of Tax	(4.6)	1.8
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	16.1	52.3
Comprehensive income attributable to noncontrolling interest	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	16.1	52.3
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	(65.7)	(77.8)
Cost of revenues	(75.0)	(84.1)
Selling, engineering, and administrative expenses	0.0	0.0
Gains on dispositions of property	0.0	0.0
Cost of revenues and operating costs	(75.0)	(84.1)
Total operating profit	9.3	6.3
Other (income) expense	0.0	0.0
Equity in earnings of subsidiaries, net of taxes	(74.6)	(100.4)
Income before income taxes	(65.3)	(94.1)
Provision (benefit) for income taxes	(1.4)	(4.6)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(63.9)	(89.5)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0.0	0.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(63.9)	(89.5)
Net Income (Loss) Attributable to Noncontrolling Interest	(0.5)	1.4
Net Income (Loss) Attributable to Parent	(63.4)	(90.9)
Other Comprehensive Income (Loss), Net of Tax	0.0	0.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(63.9)	(89.5)
Comprehensive income attributable to noncontrolling interest	(0.3)	1.8
Comprehensive income attributable to Trinity Industries, Inc.	$ (63.6)	$ (91.3)