Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 56.4	$ 21.2	$ 83.8	$ 34.9
Other comprehensive income (loss):
Unrealized gains (losses) arising during the period, net of tax benefit (expense) of $1.7, $(2.7), $(1.7), and $(2.8)	(5.5)	8.9	5.9	9.4
Reclassification adjustments for gains included in net income, net of tax (expense) benefit of $(1.7), $(1.1), $(2.9), and $9.9	(5.4)	(3.9)	(9.3)	(18.8)
Other Comprehensive Income (Loss), Net of Tax, Total	(10.9)	5.0	(3.4)	(9.4)
Comprehensive income	45.5	26.2	80.4	25.5
Less: comprehensive income attributable to noncontrolling interest	2.1	4.3	5.9	6.2
Comprehensive income attributable to Trinity Industries, Inc.	$ 43.4	$ 21.9	$ 74.5	$ 19.3