Earning Per Common Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Computation of basic and diluted net income attributable to Trinity Industries, Inc
Net income attributable to Trinity Industries, Inc.	$ 56.1	$ 31.9	$ 30.0	$ 24.2	$ 17.3	$ 29.7	$ 18.4	$ 2.0	$ 142.2	$ 67.4	$ (137.7)
Unvested restricted share participation									(4.8)	(2.3)	(1.0)
Net income attributable to Trinity Industries, Inc. - basic									137.4	65.1	(138.7)
Net income attributable to Trinity Industries, Inc. - basic, Average Shares									77.5	76.8	76.4
Net income attributable to Trinity Industries, Inc. - basic, EPS									$ 1.77	$ 0.85	$ (1.81)
Effect of dilutive securities:
Stock options									0.3	0.2
Net income attributable to Trinity Industries, Inc - diluted									$ 137.4	$ 65.1	$ (138.7)
Net income attributable to Trinity Industries, Inc. - diluted, Average Shares									77.8	77.0	76.4
Net income attributable to Trinity Industries, Inc. - diluted, EPS	$ 0.7	$ 0.40	$ 0.37	$ 0.30	$ 0.22	$ 0.37	$ 0.23	$ 0.02	$ 1.77	$ 0.85	$ (1.81)
Net Income Per Common Share (Textual) [Abstract]
Total weighted average restricted shares and antidilutive stock options									3.0	2.8	3.7