Financial Statements for Guarantors of the Senior Notes - Statement of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Income Statements, Captions [Line Items]
Revenues	$ 942.3	$ 905.5	$ 1,773.6	$ 1,782.8
Cost of revenues	718.1	682.3	1,348.2	1,342.5
Selling, engineering, and administrative expenses	110.4	113.0	215.3	215.5
Gains on dispositions of property	11.7	24.4	14.0	25.7
Cost of revenues and operating costs	816.8	770.9	1,549.5	1,532.3
Total operating profit	125.5	134.6	224.1	250.5
Other (income) expense	39.4	43.3	81.6	86.7
Equity in earnings of subsidiaries, net of taxes	0.0	0.0	0.0	0.0
Income before income taxes	86.1	91.3	142.5	163.8
Provision (benefit) for income taxes	20.6	37.3	35.4	58.1
Net income	65.5	54.0	107.1	105.7
Net income attributable to noncontrolling interest	1.4	2.9	2.8	8.6
Net income attributable to Trinity Industries, Inc.	64.1	51.1	104.3	97.1
Other comprehensive income (loss)	(0.5)	2.2	1.4	4.3
Comprehensive income	65.0	56.2	108.5	110.0
Comprehensive income attributable to noncontrolling interest	1.8	3.6	3.6	10.1
Comprehensive income attributable to Trinity Industries, Inc.	63.2	52.6	104.9	99.9
Reportable legal entities | Parent
Condensed Income Statements, Captions [Line Items]
Revenues	0.0	0.0	0.0	0.0
Cost of revenues	0.5	1.4	0.7	3.8
Selling, engineering, and administrative expenses	41.5	36.0	79.3	68.9
Gains on dispositions of property	1.3	0.1	1.4	0.6
Cost of revenues and operating costs	40.7	37.3	78.6	72.1
Total operating profit	(40.7)	(37.3)	(78.6)	(72.1)
Other (income) expense	(0.6)	5.0	1.8	11.2
Equity in earnings of subsidiaries, net of taxes	97.4	103.1	181.6	162.3
Income before income taxes	57.3	60.8	101.2	79.0
Provision (benefit) for income taxes	(6.8)	9.7	(3.1)	(18.1)
Net income	64.1	51.1	104.3	97.1
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Trinity Industries, Inc.	64.1	51.1	104.3	97.1
Other comprehensive income (loss)	0.1	1.2	0.4	2.2
Comprehensive income	64.2	52.3	104.7	99.3
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	64.2	52.3	104.7	99.3
Reportable legal entities | Combined Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	549.3	564.7	1,032.3	1,116.2
Cost of revenues	453.2	455.8	850.0	899.5
Selling, engineering, and administrative expenses	34.9	33.9	67.4	64.7
Gains on dispositions of property	7.6	20.9	9.5	21.0
Cost of revenues and operating costs	480.5	468.8	907.9	943.2
Total operating profit	68.8	95.9	124.4	173.0
Other (income) expense	7.8	8.6	15.9	15.2
Equity in earnings of subsidiaries, net of taxes	21.5	26.1	46.8	43.2
Income before income taxes	82.5	113.4	155.3	201.0
Provision (benefit) for income taxes	17.0	31.5	27.4	70.5
Net income	65.5	81.9	127.9	130.5
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Trinity Industries, Inc.	65.5	81.9	127.9	130.5
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income	65.5	81.9	127.9	130.5
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	65.5	81.9	127.9	130.5
Reportable legal entities | Combined Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	524.1	473.4	1,035.1	937.2
Cost of revenues	404.0	364.6	805.3	721.4
Selling, engineering, and administrative expenses	34.0	43.1	68.6	81.9
Gains on dispositions of property	2.8	3.4	3.1	4.1
Cost of revenues and operating costs	435.2	404.3	870.8	799.2
Total operating profit	88.9	69.1	164.3	138.0
Other (income) expense	32.2	29.7	63.9	60.3
Equity in earnings of subsidiaries, net of taxes	0.0	0.0	0.0	0.0
Income before income taxes	56.7	39.4	100.4	77.7
Provision (benefit) for income taxes	15.4	9.8	20.7	19.5
Net income	41.3	29.6	79.7	58.2
Net income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Net income attributable to Trinity Industries, Inc.	41.3	29.6	79.7	58.2
Other comprehensive income (loss)	(0.6)	1.0	1.0	2.1
Comprehensive income	40.7	30.6	80.7	60.3
Comprehensive income attributable to noncontrolling interest	0.0	0.0	0.0	0.0
Comprehensive income attributable to Trinity Industries, Inc.	40.7	30.6	80.7	60.3
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenues	(131.1)	(132.6)	(293.8)	(270.6)
Cost of revenues	(139.6)	(139.5)	(307.8)	(282.2)
Selling, engineering, and administrative expenses	0.0	0.0	0.0	0.0
Gains on dispositions of property	0.0	0.0	0.0	0.0
Cost of revenues and operating costs	(139.6)	(139.5)	(307.8)	(282.2)
Total operating profit	8.5	6.9	14.0	11.6
Other (income) expense	0.0	0.0	0.0	0.0
Equity in earnings of subsidiaries, net of taxes	(118.9)	(129.2)	(228.4)	(205.5)
Income before income taxes	(110.4)	(122.3)	(214.4)	(193.9)
Provision (benefit) for income taxes	(5.0)	(13.7)	(9.6)	(13.8)
Net income	(105.4)	(108.6)	(204.8)	(180.1)
Net income attributable to noncontrolling interest	1.4	2.9	2.8	8.6
Net income attributable to Trinity Industries, Inc.	(106.8)	(111.5)	(207.6)	(188.7)
Other comprehensive income (loss)	0.0	0.0	0.0	0.0
Comprehensive income	(105.4)	(108.6)	(204.8)	(180.1)
Comprehensive income attributable to noncontrolling interest	1.8	3.6	3.6	10.1
Comprehensive income attributable to Trinity Industries, Inc.	$ (107.2)	$ (112.2)	$ (208.4)	$ (190.2)