Financial Statements for Guarantors of the Senior Notes - Statement of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Income Statements, Captions [Line Items]
Revenues	$ 831.3	$ 877.3
Cost of revenues	630.1	660.2
Selling, engineering, and administrative expenses	104.9	102.5
Gains/(losses) on dispositions of property	2.3	1.3
Cost of revenues and operating costs	732.7	761.4
Total operating profit	98.6	115.9
Other (income) expense	42.2	43.4
Equity in earnings of subsidiaries, net of taxes	0.0	0.0
Income before income taxes	56.4	72.5
Provision (benefit) for income taxes	14.8	20.8
Net income	41.6	51.7
Net income attributable to noncontrolling interest	1.4	5.7
Net income attributable to Trinity Industries, Inc.	40.2	46.0
Other comprehensive income (loss)	1.9	2.1
Comprehensive income	43.5	53.8
Comprehensive income attributable to noncontrolling interest	1.8	6.5
Comprehensive income attributable to Trinity Industries, Inc.	41.7	47.3
Reportable legal entities | Parent
Condensed Income Statements, Captions [Line Items]
Revenues	0.0	0.0
Cost of revenues	0.2	2.4
Selling, engineering, and administrative expenses	37.8	32.8
Gains/(losses) on dispositions of property	0.1	0.5
Cost of revenues and operating costs	37.9	34.7
Total operating profit	(37.9)	(34.7)
Other (income) expense	2.4	6.1
Equity in earnings of subsidiaries, net of taxes	84.4	57.6
Income before income taxes	44.1	16.8
Provision (benefit) for income taxes	3.9	(29.2)
Net income	40.2	46.0
Net income attributable to noncontrolling interest	0.0	0.0
Net income attributable to Trinity Industries, Inc.	40.2	46.0
Other comprehensive income (loss)	0.1	1.0
Comprehensive income	40.3	47.0
Comprehensive income attributable to noncontrolling interest	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	40.3	47.0
Reportable legal entities | Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	483.1	550.6
Cost of revenues	396.9	442.2
Selling, engineering, and administrative expenses	32.5	30.8
Gains/(losses) on dispositions of property	1.9	0.1
Cost of revenues and operating costs	427.5	472.9
Total operating profit	55.6	77.7
Other (income) expense	8.1	6.6
Equity in earnings of subsidiaries, net of taxes	25.2	17.0
Income before income taxes	72.7	88.1
Provision (benefit) for income taxes	10.3	40.4
Net income	62.4	47.7
Net income attributable to noncontrolling interest	0.0	0.0
Net income attributable to Trinity Industries, Inc.	62.4	47.7
Other comprehensive income (loss)	0.0	0.0
Comprehensive income	62.4	47.7
Comprehensive income attributable to noncontrolling interest	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	62.4	47.7
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	511.1	464.0
Cost of revenues	401.4	356.9
Selling, engineering, and administrative expenses	34.6	38.9
Gains/(losses) on dispositions of property	0.3	0.7
Cost of revenues and operating costs	435.7	395.1
Total operating profit	75.4	68.9
Other (income) expense	31.7	30.7
Equity in earnings of subsidiaries, net of taxes	0.0	0.0
Income before income taxes	43.7	38.2
Provision (benefit) for income taxes	5.2	9.8
Net income	38.5	28.4
Net income attributable to noncontrolling interest	0.0	0.0
Net income attributable to Trinity Industries, Inc.	38.5	28.4
Other comprehensive income (loss)	1.8	1.1
Comprehensive income	40.3	29.5
Comprehensive income attributable to noncontrolling interest	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	40.3	29.5
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	(162.9)	(137.3)
Cost of revenues	(168.4)	(141.3)
Selling, engineering, and administrative expenses	0.0	0.0
Gains/(losses) on dispositions of property	0.0	0.0
Cost of revenues and operating costs	(168.4)	(141.3)
Total operating profit	5.5	4.0
Other (income) expense	0.0	0.0
Equity in earnings of subsidiaries, net of taxes	(109.6)	(74.6)
Income before income taxes	(104.1)	(70.6)
Provision (benefit) for income taxes	(4.6)	(0.2)
Net income	(99.5)	(70.4)
Net income attributable to noncontrolling interest	1.4	5.7
Net income attributable to Trinity Industries, Inc.	(100.9)	(76.1)
Other comprehensive income (loss)	0.0	0.0
Comprehensive income	(99.5)	(70.4)
Comprehensive income attributable to noncontrolling interest	1.8	6.5
Comprehensive income attributable to Trinity Industries, Inc.	$ (101.3)	$ (76.9)