Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 27.4	$ 13.7
Other comprehensive income (loss):
Unrealized gains arising during the period, net of tax benefit (expense) of $3.4 and $(0.1)	11.4	0.5
Reclassification adjustments for gains included in net income, net of tax (expense) benefit of $(1.2) and $11.0	(3.9)	(14.9)
Other Comprehensive Income (Loss), Net of Tax, Total	7.5	(14.4)
Comprehensive income (loss)	34.9	(0.7)
Less: comprehensive income attributable to noncontrolling interest	3.8	1.9
Comprehensive income (loss) attributable to Trinity Industries, Inc.	$ 31.1	$ (2.6)