Consolidated Statement of Stockholders' Equity (unaudited) - USD ($) shares in Millions, $ in Millions		Total	Trinity Stockholders’ Equity	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated other comprehensive income (loss)	Treasury Stock	Noncontrolling Interest
$0.01 Par Value		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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	$ 1,012.4	$ 0.8	$ 0.0	$ 992.6	$ 19.7	$ (0.7)	$ 257.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		13.7	4.4			4.4			9.3
Other comprehensive income		(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)		0.4			(0.8)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Mar. 31, 2023		$ 1,250.4	994.2	0.8	6.6	975.6	12.7	(1.5)	256.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared		$ 0.26
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2022		$ 1,269.6	1,012.4	0.8	0.0	992.6	19.7	(0.7)	257.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		34.9
Other comprehensive income		(9.4)
Stock-based compensation expense		12.7
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jun. 30, 2023		$ 1,249.0	994.6	$ 0.8	5.9	971.0	17.6	$ (0.7)	254.4
$0.01 Par Value		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Issued				(81.1)				0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Mar. 31, 2023		$ 1,250.4	994.2	$ 0.8	6.6	975.6	12.7	$ (1.5)	256.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		21.2	17.0			17.0			4.2
Other comprehensive income		5.0	4.9				4.9		0.1
Cash dividends declared on common stock (1)	[1]	(21.6)	(21.6)			(21.6)
Distributions to noncontrolling interest		(6.1)							(6.1)
Stock-based compensation expense		6.5	6.5		6.5
Restricted shares, net, (in shares)				(1.0)				(0.3)
Settlement of share-based awards, net		(6.4)	(6.4)					$ (6.4)
Treasury Stock, Shares, Retired				(0.3)				(0.3)
Retirement of treasury stock		0.0	0.0		(7.2)			$ (7.2)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jun. 30, 2023		$ 1,249.0	994.6	$ 0.8	5.9	971.0	17.6	$ (0.7)	254.4
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				(81.8)				0.0
$0.01 Par Value		$ 0.01
Common Stock, Shares, Issued				(81.8)				0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2023		$ 1,275.5	1,037.1	$ 0.8	15.4	1,010.5	11.0	$ (0.6)	238.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		27.4	23.7			23.7			3.7
Other comprehensive income		7.5	7.4				7.4		0.1
Cash dividends declared on common stock (1)	[2]	(23.3)	(23.3)			(23.3)
Distributions to noncontrolling interest		(3.0)							(3.0)
Stock-based compensation expense		4.7	4.7		4.7
Settlement of share-based awards, net		(0.3)	(0.3)		0.1			(0.4)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Mar. 31, 2024		$ 1,288.5	1,049.3	0.8	20.2	1,010.9	18.4	(1.0)	239.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared		$ 0.28
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Dec. 31, 2023		$ 1,275.5	1,037.1	0.8	15.4	1,010.5	11.0	(0.6)	238.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		83.8
Other comprehensive income		(3.4)							0.2
Stock-based compensation expense		10.6
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jun. 30, 2024		$ 1,304.0	1,065.5	$ 0.8	15.9	1,042.0	7.4	$ (0.6)	238.5
$0.01 Par Value		$ 0.01
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Issued				(81.8)				0.0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Mar. 31, 2024		$ 1,288.5	1,049.3	$ 0.8	20.2	1,010.9	18.4	$ (1.0)	239.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		56.4	54.4			54.4			2.0
Other comprehensive income		(10.9)	(11.0)				(11.0)		0.1
Cash dividends declared on common stock (1)	[2]	(23.3)	(23.3)			(23.3)
Distributions to noncontrolling interest		(2.8)							(2.8)
Stock-based compensation expense		5.9	5.9		5.9
Restricted shares, net, (in shares)				(0.9)				(0.3)
Settlement of share-based awards, net		(8.9)	(8.9)		0.2			$ (9.1)
Shares repurchased								0.0
Shares repurchased		(0.9)	(0.9)					$ (0.9)
Treasury Stock, Shares, Retired				(0.3)				(0.3)
Retirement of treasury stock		0.0	0.0		(10.4)			$ (10.4)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance at Jun. 30, 2024		$ 1,304.0	$ 1,065.5	$ 0.8	$ 15.9	$ 1,042.0	$ 7.4	$ (0.6)	$ 238.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared		$ 0.28
$0.01 Par Value		$ 0.01
Common Stock, Shares, Issued				(82.4)				0.0

[1] Dividends of $0.26 per common share for for all periods presented in 2023

[2] Dividends of $0.28 per common share for all periods presented in 2024.