Selected Quarterly Financial Data (Unaudited) - Selected Quarterly Financial Data (Unaudited) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Total revenues	$ 906.4	$ 973.6	$ 905.5	$ 877.3	$ 1,103.8	$ 1,111.7	$ 1,184.9	$ 1,187.9	$ 3,662.8	$ 4,588.3	$ 6,392.7
Cost of revenues:
Total cost of revenues	681.7	722.2	681.9	659.7	841.2	827.3	897.7	889.9	2,745.5	3,456.1	4,656.2
Selling, engineering, and administrative expenses	125.2	114.5	112.8	102.3	101.9	102.3	106.7	96.5	454.8	407.4	476.4
Gains on disposition of property	44.8	16.1	24.4	1.3	2.9	1.5	11.1	1.9	86.6	17.4	178.8
Operating profit	144.3	153.0	135.2	116.6	163.6	183.6	191.6	203.4	549.1	742.2	1,438.9
Income before income taxes	100.6	107.6	91.3	72.5	115.6	139.5	152.2	159.5	372.0	566.8	1,252.0
Provision	(439.4)	39.7	37.3	20.8	41.4	49.9	53.4	57.4	(341.6)	202.1	426.0
Net income	540.0	67.9	54.0	51.7	74.2	89.6	98.8	102.1	713.6	364.7	826.0
Net income attributable to Trinity Industries, Inc.	$ 538.5	$ 66.9	$ 51.1	$ 46.0	$ 67.6	$ 84.2	$ 94.6	$ 97.2	$ 702.5	$ 343.6	$ 796.5
Net income attributable to Trinity Industries, Inc. per common share:
Basic (in dollars per share)	$ 3.56	$ 0.44	$ 0.34	$ 0.30	$ 0.44	$ 0.55	$ 0.62	$ 0.64	$ 4.62	$ 2.25	$ 5.14
Diluted (in dollars per share)	$ 3.42	$ 0.43	$ 0.33	$ 0.30	$ 0.44	$ 0.55	$ 0.62	$ 0.64	$ 4.52	$ 2.25	$ 5.08
Manufacturing
Revenues:
Total revenues	$ 709.6	$ 698.7	$ 713.6	$ 698.7	$ 926.0	$ 938.5	$ 888.8	$ 1,010.1	$ 2,820.6	$ 3,763.4	$ 5,301.1
Cost of revenues:
Total cost of revenues	581.8	565.6	589.7	576.1	761.2	745.4	719.1	793.9	2,313.2	3,019.6	4,043.9
Selling, engineering, and administrative expenses									237.0	231.0	271.4
Leasing
Revenues:
Total revenues	196.8	274.9	191.9	178.6	177.8	173.2	296.1	177.8	842.2	824.9	1,091.6
Cost of revenues:
Total cost of revenues	$ 99.9	$ 156.6	$ 92.2	$ 83.6	$ 80.0	$ 81.9	$ 178.6	$ 96.0	432.3	436.5	612.3
Selling, engineering, and administrative expenses									$ 50.5	$ 45.4	$ 52.4