Consolidated Statement of Stockholders' Equity (unaudited) - USD ($) shares in Millions, $ in Millions		Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated other comprehensive income (loss)	Treasury Stock	Trinity Stockholders’ Equity	Noncontrolling Interest
$0.01 Par Value		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Issued			(83.3)				0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2021		$ 1,296.8	$ 0.8	$ 0.0	$ 1,046.6	$ (17.0)	$ (0.6)	$ 1,029.8	$ 267.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		1.9			(0.7)			(0.7)	2.6
Other comprehensive loss		17.3				17.1		17.1	0.2
Cash dividends declared on common stock (1)	[1]	(19.3)			(19.3)			(19.3)
Distributions to noncontrolling interest		(6.2)							(6.2)
Stock-based compensation expense		5.1		5.1				5.1
Settlement of share-based awards, net		0.0		0.2			(0.2)	0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Mar. 31, 2022		$ 1,295.6	$ 0.8	5.3	1,026.6	0.1	$ (0.8)	1,032.0	263.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared		$ 0.23
$0.01 Par Value		0.01
Common Stock, Shares, Issued			(83.3)				0.0
$0.01 Par Value		$ 0.01
Common Stock, Shares, Issued			(81.1)				0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2022		$ 1,269.6	$ 0.8	0.0	992.6	19.7	$ (0.7)	1,012.4	257.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		13.7			4.4			4.4	9.3
Other comprehensive loss		(14.4)				(7.0)		(7.0)	(7.4)
Cash dividends declared on common stock (1)	[1]	(21.4)			(21.4)			(21.4)
Distributions to noncontrolling interest		(2.9)							(2.9)
Stock-based compensation expense		6.2		6.2				6.2
Settlement of share-based awards, net		(0.4)		0.4			(0.8)	(0.4)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Mar. 31, 2023		$ 1,250.4	$ 0.8	$ 6.6	$ 975.6	$ 12.7	$ (1.5)	$ 994.2	$ 256.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared		$ 0.26
$0.01 Par Value		$ 0.01
Common Stock, Shares, Issued			(81.1)				0.0

[1] Dividends of $0.26 and $0.23 per common share for the three months ended March 31, 2023 and 2022, respectively