Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 89.6	$ 212.2	$ 290.5	$ 622.0
Derivative financial instruments:
Unrealized losses arising during the period, net of tax expense (benefit) of $0.1, $(0.2), $(0.1), and $(0.4)	0.0	(0.5)	(0.7)	(0.8)
Reclassification adjustments for losses included in net income, net of tax benefit of $0.1, $0.2, $0.6, and $3.3	1.2	1.2	3.4	7.6
Currency translation adjustment	(0.4)	(2.6)	1.4	(5.2)
Defined benefit plans:
Amortization of net actuarial losses, net of tax benefit of $0.4, $0.5, $1.4, and $1.5	0.8	0.8	2.4	2.4
Other comprehensive income	1.6	(1.1)	6.5	4.0
Comprehensive income	91.2	211.1	297.0	626.0
Less: comprehensive income attributable to noncontrolling interest	6.2	8.4	16.5	27.5
Comprehensive income attributable to Trinity Industries, Inc.	$ 85.0	$ 202.7	$ 280.5	$ 598.5