Earnings Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Income Per Common Share (Textual) [Abstract]
Total weighted average restricted shares and antidilutive stock options (in shares)									7.4	7.0	6.1
Computation of basic and diluted net income attributable to Trinity Industries, Inc
Net income from continuing operations	$ 146.4	$ 156.3	$ 173.3	$ 233.3	$ 118.9	$ 105.8	$ 89.2	$ 72.2	$ 709.3	$ 386.1	$ 251.9
Less: net income (loss) from continuing operations attributable to noncontrolling interest									31.1	16.9	(1.5)
Net income from continuing operations attributable to Trinity Industries, Inc.									678.2	369.2	253.4
Unvested restricted share participation									(22.1)	(12.0)	(7.7)
Net income from continuing operations attributable to Trinity Industries, Inc. - basic, Income (Loss)									656.1	357.2	245.7
Net income from continuing operations attributable to Trinity Industries, Inc. - basic, Average Shares									151.0	152.8	154.7
Net income from continuing operations attributable to Trinity Industries, Inc. - basic, EPS (in dollars per share)	$ 0.89	$ 0.95	$ 1.05	$ 1.46	$ 0.72	$ 0.63	$ 0.53	$ 0.46	$ 4.35	$ 2.34	$ 1.59
Effect of dilutive securities:
Stock options, Income (Loss)									0	0	0
Stock options, Average Shares									0.1	0.1	0.4
Convertible subordinated notes, Income (Loss)									0.7	0	0
Convertible subordinated notes, Average Shares									5.6	0	0
Discontinued operations, Convertible subordinated notes, Income (Loss)									0	0	0
Net income from continuing operations attributable to Trinity Industries, Inc. - diluted, Income (Loss)									656.8	357.2	245.7
Net income from continuing operations attributable to Trinity Industries, Inc. - diluted, Average Shares									156.7	152.9	155.1
Net income from continuing operations attributable to Trinity Industries, Inc. - diluted, EPS (in dollars per share)	$ 0.86	$ 0.90	$ 1.01	$ 1.42	$ 0.72	$ 0.63	$ 0.53	$ 0.46	$ 4.19	$ 2.34	$ 1.58
Discontinued operations, net of tax	(0.1)	0.6	(0.2)	(0.3)	0.4	0.3	(1.0)	6.6	0	6.3	1.8
Unvested restricted share participation									0	(0.2)	(0.1)
Net income from discontinued operations, net of taxes - basic, Income (Loss)									0	6.1	1.7
Net income from discontinued operations, net of taxes - basic, EPS (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.01)	$ 0.04	$ 0.00	$ 0.04	$ 0.01
Net income from discontinued operations, net of taxes - diluted, Income (Loss)									$ 0	$ 6.1	$ 1.7
Net income from discontinued operations, net of taxes - diluted, EPS (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.01)	$ 0.04	$ 0.00	$ 0.04	$ 0.01