Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 36.0	$ 35.5	$ 83.1	$ 119.3
Other comprehensive income (loss):
Unrealized gains (losses) arising during the period, net of tax benefit (expense) of $(0.8), $3.9, $(0.4), and $2.2	3.2	(13.2)	1.7	(7.3)
Reclassification adjustments for gains included in net income, net of tax expense of $1.0, $1.3, $0.5, and $4.2	(3.0)	(3.8)	(1.3)	(13.1)
Amortization of net actuarial losses, net of tax benefit of $—, $—, $—, and $—	0.1	0.1	0.1	0.1
Other Comprehensive Income (Loss), Net of Tax, Total	0.3	(16.9)	0.5	(20.3)
Comprehensive income	36.3	18.6	83.6	99.0
Less: comprehensive income attributable to noncontrolling interest	5.7	4.2	16.8	10.1
Comprehensive income attributable to Trinity Industries, Inc.	$ 30.6	$ 14.4	$ 66.8	$ 88.9