Consolidated Statements of Stockholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Trinity Stockholders' Equity	Noncontrolling Interest
Beginning balance at Dec. 31, 2009	$ 1,830.8	$ 81.7	$ 598.4	$ 1,158.5	$ (98.0)	$ (39.7)	$ 1,700.9	$ 129.9
Beginning balance, Shares at Dec. 31, 2009		81,700,000				(2,500,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	75.4			67.4			67.4	8.0
Other comprehensive income (loss)	(6.6)				2.5		2.5	(9.1)
Cash dividends on common stock	(25.4)			(25.4)			(25.4)
Restricted shares issued, net	6.9		(2.3)			9.2	6.9
Restricted shares issued, net, Shares						400,000
Stock options exercised	1.7		(0.8)			2.5	1.7
Stock options exercised, Shares						100,000
Income tax (expense) benefit from stock options exercised	(0.2)		(0.2)				(0.2)
Stock-based compensation expense	0.6		0.6				0.6
Purchase / Reclassification of purchase of additional interest in TRIP Holdings	(37.6)		10.3				10.3	(47.9)
Other	0.1		0.1				0.1
Other, Shares						100,000
Ending balance at Dec. 31, 2010	1,845.7	81.7	606.1	1,200.5	(95.5)	(28.0)	1,764.8	80.9
Ending balance, Shares at Dec. 31, 2010		81,700,000				(1,900,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	145.7			142.2			142.2	3.5
Other comprehensive income (loss)	(28.4)				(28.5)		(28.5)	0.1
Cash dividends on common stock	(28.0)			(28.0)			(28.0)
Restricted shares issued, net	7.0		6.7			0.3	7.0
Restricted shares issued, net, Shares						200,000
Stock options exercised	2.1		(0.5)			2.6	2.1
Stock options exercised, Shares						200,000
Income tax (expense) benefit from stock options exercised	3.5		3.5				3.5
Stock-based compensation expense	0.6		0.6				0.6
Purchase / Reclassification of purchase of additional interest in TRIP Holdings	15.5		15.5		(15.5)
Tax expense allocation related to TRIP Holdings unrealized loss on derivative financial instruments			(5.5)		5.5
Other	0.1		0.1				0.1
Ending balance at Dec. 31, 2011	1,948.3	81.7	626.5	1,314.7	(134.0)	(25.1)	1,863.8	84.5
Ending balance, Shares at Dec. 31, 2011		81,700,000				(1,500,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	253.7			255.2			255.2	(1.5)
Other comprehensive income (loss)	(14.5)				(16.1)		(16.1)	1.6
Cash dividends on common stock	(33.2)			(33.2)			(33.2)
Restricted shares issued, net	24.7		26.4			(1.7)	24.7
Restricted shares issued, net, Shares						400,000
Stock options exercised	4.1		(0.7)			4.8	4.1
Stock options exercised, Shares	419,158					300,000
Income tax (expense) benefit from stock options exercised	0.2
Stock-based compensation expense	0.2		0.2				0.2
Shares repurchased	(45.2)					(45.2)	(45.2)
Shares repurchased, Shares	(1,834,221)					(1,800,000)
Other	(0.7)					(0.7)	(0.7)
Other, Shares						0
Ending balance at Dec. 31, 2012	$ 2,137.6	$ 81.7	$ 652.6	$ 1,536.7	$ (150.1)	$ (67.9)	$ 2,053.0	$ 84.6
Ending balance, Shares at Dec. 31, 2012		81,700,000				(2,600,000)