Selected Quarterly Financial Data (Unaudited) - Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues [Abstract]
Total revenues	$ 735.0	$ 606.9	$ 634.0	$ 533.2	$ 615.4	$ 655.7	$ 595.7	$ 530.6	$ 2,509.1	$ 2,397.4	$ 3,089.8
Cost of revenues:
Total cost of revenues	590.5	466.5	481.9	399.9	455.8	480.8	450.8	387.8	1,938.8	1,775.2	2,312.0
Selling, engineering, and administrative expenses	72.0	75.6	75.6	73.4	88.5	85.8	85.8	79.2	296.6	339.3	313.9
Gains on disposition of property	17.3	10.4	11.5	2.2	44.4	16.0	24.0	1.0	41.4	85.4	15.0
Operating profit	89.8	75.2	88.0	62.1	115.5	105.1	83.1	64.6	315.1	368.3	478.9
Income (loss) before income taxes	45.7	35.2	49.8	20.9	74.0	60.2	38.8	22.4	151.6	195.4	310.0
Provision	17.7	6.7	12.5	5.7	(457.9)	23.4	16.7	3.0	42.6	(414.8)	106.8
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	28.0	28.5	37.3	15.2	531.9	36.8	22.1	19.4	109.0	610.2	203.2
Net income	27.7	28.3	65.5	41.6	540.0	67.9	54.0	51.7	163.1	713.6	364.7
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(0.3)	(0.2)	28.2	26.4	8.1	31.1	31.9	32.3	54.1	103.4	161.5
Net income attributable to Trinity Industries, Inc.	$ 27.3	$ 27.7	$ 64.1	$ 40.2	$ 538.5	$ 66.9	$ 51.1	$ 46.0	$ 159.3	$ 702.5	$ 343.6
Net income attributable to Trinity Industries, Inc. per common share:
Basic (in dollars per share)	$ 0.20	$ 0.19	$ 0.43	$ 0.27	$ 3.56	$ 0.44	$ 0.34	$ 0.30	$ 1.09	$ 4.62	$ 2.25
Diluted (in dollars per share)	0.19	0.19	0.43	0.26	3.42	0.43	0.33	0.30	1.07	4.52	2.25
Income (Loss) from Continuing Operations, Per Basic Share		0.19	0.24	0.09	3.51	0.23	0.13	0.09	0.72	3.94	1.19
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	$ 0.00	0.00	0.19	0.18	0.05	0.21	0.21	0.21	0.37	0.68	1.06
Income (Loss) from Continuing Operations, Per Diluted Share		$ 0.19	$ 0.24	$ 0.09	$ 3.37	$ 0.23	$ 0.12	$ 0.09	$ 0.70	$ 3.85	$ 1.19
Manufacturing
Revenues [Abstract]
Total revenues	$ 507.7	$ 379.7	$ 420.8	$ 358.9	$ 418.6	$ 380.8	$ 403.8	$ 352.0	$ 1,667.1	$ 1,555.2	$ 2,264.9
Cost of revenues:
Total cost of revenues	456.4	333.5	363.4	306.5	355.8	324.2	358.6	304.2	1,459.8	1,342.8	1,875.5
Selling, engineering, and administrative expenses									96.4	113.6	115.4
Leasing
Revenues [Abstract]
Total revenues	227.3	227.2	213.2	174.3	196.8	274.9	191.9	178.6	842.0	842.2	824.9
Cost of revenues:
Total cost of revenues	$ 134.1	$ 133.0	$ 118.5	$ 93.4	$ 100.0	$ 156.6	$ 92.2	$ 83.6	479.0	432.4	436.5
Selling, engineering, and administrative expenses									$ 51.1	$ 50.7	$ 45.4