Selected Quarterly Financial Data (Unaudited) (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
Revenues:
Total revenues	$ 1,661.4	$ 1,562.8	$ 1,485.3	$ 1,460.5	$ 1,256.0	$ 1,110.3	$ 1,066.1	$ 932.9	$ 6,170.0	$ 4,365.3	$ 3,811.9
Cost of revenues:
Total cost of revenues	1,275.3	1,172.2	1,098.3	1,074.0	962.7	836.3	812.2	711.1	4,619.8	3,322.3	3,051.5
Selling, engineering, and administrative expenses	110.6	113.0	96.4	83.6	80.2	70.6	71.5	69.0	403.6	291.3	224.1
Gain on disposition of property, plant, and equipment	1.0	3.6	11.4	88.4	11.3	2.2	1.0	6.7	104.4	21.2	38.5
Operating Profit	276.5	281.2	302.0	391.3	224.4	205.6	183.4	159.5	1,251.0	772.9	574.8
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
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
Net income	146.3	156.9	173.1	233.0	119.3	106.1	88.2	78.8	709.3	392.4	253.7
Net income attributable to Trinity Industries, Inc.	138.2	149.4	164.2	226.4	112.8	99.6	84.0	79.1	678.2	375.5	255.2
Basic:
Continuing operations (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
Discontinued operations (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
Basic (in dollars per share)	$ 0.89	$ 0.95	$ 1.05	$ 1.46	$ 0.72	$ 0.63	$ 0.52	$ 0.50	$ 4.35	$ 2.38	$ 1.60
Diluted:
Continuing operations (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 (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
Diluted (in dollars per share)	$ 0.86	$ 0.90	$ 1.01	$ 1.42	$ 0.72	$ 0.63	$ 0.52	$ 0.50	$ 4.19	$ 2.38	$ 1.59
Manufacturing
Revenues:
Total revenues	1,425.6	1,359.8	1,259.9	1,018.3	1,065.2	959.7	896.5	798.5	5,063.6	3,719.9	3,167.5
Cost of revenues:
Total cost of revenues	1,147.6	1,062.6	970.2	794.7	856.7	767.0	726.0	641.2	3,975.1	2,990.9	2,701.2
Selling, engineering, and administrative expenses									235.0	180.4	143.4
Leasing
Revenues:
Total revenues	235.8	203.0	225.4	442.2	190.8	150.6	169.6	134.4	1,106.4	645.4	644.4
Cost of revenues:
Total cost of revenues	127.7	109.6	128.1	279.3	106.0	69.3	86.2	69.9	644.7	331.4	350.3
Selling, engineering, and administrative expenses									$ 49.6	$ 37.6	$ 29.4