Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 54.0	$ 98.8	$ 105.7	$ 200.9
Derivative financial instruments:
Unrealized losses arising during the period, net of tax benefit of $-, $-, $-, and $0.2	(0.2)	(0.3)	(0.2)	(0.7)
Reclassification adjustments for losses included in net income, net of tax benefit of $-, $0.1, $0.3, and $0.5	1.2	1.2	2.2	2.2
Currency translation adjustment	0.5	0.3	0.8	1.8
Defined benefit plans:
Amortization of net actuarial losses, net of tax benefit of $0.5, $0.5, $0.9, and $1.0	0.7	0.8	1.5	1.6
Other comprehensive income	2.2	2.0	4.3	4.9
Comprehensive income	56.2	100.8	110.0	205.8
Less: comprehensive income attributable to noncontrolling interest	3.6	4.9	10.1	10.3
Comprehensive income attributable to Trinity Industries, Inc.	$ 52.6	$ 95.9	$ 99.9	$ 195.5