Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Computation of basic and diluted net income attributable to Trinity Industries, Inc
Net income attributable to Trinity Industries, Inc.	$ 204.3	$ 149.4	$ 596.5	$ 540.0
Unvested restricted share participation	(6.0)	(4.7)	(18.2)	(17.8)
Net income attributable to Trinity Industries, Inc. – basic	$ 198.3	$ 144.7	$ 578.3	$ 522.2
Net income attributable to Trinity Industries, Inc. - basic, Average Shares (in shares)	150.0	151.5	150.6	150.9
Net income attributable to Trinity Industries, Inc. - basic, EPS (in dollars per share)	$ 1.32	$ 0.96	$ 3.84	$ 3.46
Effect of dilutive securities:
Stock options, Income (Loss)	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Stock options, Average Shares	0.0	0.1	0.0	0.1
Convertible subordinated notes, Income (Loss)	$ 0.0	$ 0.2	$ 0.3	$ 0.6
Convertible subordinated notes, Average Shares	0.9	8.0	2.5	6.0
Net income attributable to Trinity Industries, Inc. – diluted	$ 198.3	$ 144.9	$ 578.6	$ 522.8
Net income attributable to Trinity Industries, Inc. - diluted, Average Shares	150.9	159.6	153.1	157.0
Net income attributable to Trinity Industries, Inc. - diluted, EPS (in dollars per share)	$ 1.31	$ 0.91	$ 3.78	$ 3.33