Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 713.6	$ 364.7	$ 826.0
Derivative financial instruments:
Unrealized losses arising during the period, net of tax benefit of $0.2, $-, and $0.2	(0.9)	(0.3)	(0.7)
Reclassification adjustments for losses included in net income, net of tax benefit of $0.7, $0.7, and $3.4	3.9	4.6	9.0
Currency translation adjustment	1.3	0.8	(6.0)
Defined benefit plans:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $1.6, $(2.0), and $(3.4)	3.6	(3.3)	(6.0)
Amortization of net actuarial losses, net of tax expense of $1.5, $1.9, and $1.8	3.4	3.2	3.2
Total other comprehensive income (loss)	11.3	5.0	(0.5)
Comprehensive income	724.9	369.7	825.5
Less: comprehensive income attributable to noncontrolling interest	13.7	24.2	32.5
Comprehensive income attributable to Trinity Industries, Inc.	$ 711.2	$ 345.5	$ 793.0