Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues [Abstract]
Revenues	$ 930.9	$ 973.6	$ 2,704.5	$ 2,756.4
Cost of revenues:
Total cost of revenues	752.0	722.7	2,100.2	2,065.2
Selling, engineering, and administrative expenses:
Total selling, engineering, and administrative expenses	111.1	114.6	326.4	330.1
Gains (losses) on dispositions of property:
Net gains on railcar lease fleet sales owned more than one year at the time of sale	9.4	16.5	21.0	40.2
Other	1.7	(0.4)	4.1	1.6
Total gains (losses) on disposition of property	11.1	16.1	25.1	41.8
Total operating profit	78.9	152.4	303.0	402.9
Other (income) expense:
Interest income	(2.4)	(3.1)	(10.0)	(7.1)
Interest expense	42.8	46.8	132.9	137.5
Other, net	(0.5)	1.1	(1.4)	1.1
Total other (income) expense	39.9	44.8	121.5	131.5
Income before income taxes	39.0	107.6	181.5	271.4
Provision for income taxes	10.7	39.7	46.1	97.8
Net income	28.3	67.9	135.4	173.6
Net income attributable to noncontrolling interest	0.6	1.0	3.4	9.6
Net income attributable to Trinity Industries, Inc.	$ 27.7	$ 66.9	$ 132.0	$ 164.0
Net income attributable to Trinity Industries, Inc. per common share:
Basic (in dollars per share)	$ 0.19	$ 0.44	$ 0.89	$ 1.08
Diluted (in dollars per share)	$ 0.19	$ 0.43	$ 0.87	$ 1.06
Weighted average number of shares outstanding:
Basic (in shares)	145.0	148.0	146.1	148.6
Diluted (in shares)	145.8	151.3	148.8	151.1
Dividends declared per common share (in dollars per share)	$ 0.13	$ 0.13	$ 0.39	$ 0.37
Manufacturing
Revenues [Abstract]
Revenues	$ 703.7	$ 698.7	$ 2,089.8	$ 2,111.0
Cost of revenues:
Total cost of revenues	619.0	566.1	1,755.3	1,732.8
Selling, engineering, and administrative expenses:
Total selling, engineering, and administrative expenses	57.6	59.2	165.2	177.3
Leasing
Revenues [Abstract]
Revenues	227.2	274.9	614.7	645.4
Cost of revenues:
Total cost of revenues	133.0	156.6	344.9	332.4
Selling, engineering, and administrative expenses:
Total selling, engineering, and administrative expenses	11.9	14.0	36.7	37.9
Other
Selling, engineering, and administrative expenses:
Total selling, engineering, and administrative expenses	$ 41.6	$ 41.4	$ 124.5	$ 114.9