Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 163.1	$ 713.6	$ 364.7
Derivative financial instruments:
Unrealized losses arising during the period, net of tax benefit of $3.0, $0.2, and $-	(9.6)	(0.9)	(0.3)
Reclassification adjustments for losses included in net income, net of tax benefit of $0.4, $0.7, and $0.7	2.3	3.9	4.6
Currency translation adjustment	0.0	1.3	0.8
Defined benefit plans:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $(2.9), $1.6, and $(2.0)	(9.5)	3.6	(3.3)
Amortization of net actuarial (gains) losses, net of tax expense of $1.1, $1.5, and $1.9	3.6	3.4	3.2
Total other comprehensive income (loss)	(13.2)	11.3	5.0
Comprehensive income	149.9	724.9	369.7
Less: comprehensive income attributable to noncontrolling interest	5.2	13.7	24.2
Comprehensive income attributable to Trinity Industries, Inc.	$ 144.7	$ 711.2	$ 345.5