Consolidated Statement of Stockholders' Equity (Unaudited) (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, 2008	$ 1,912.3	$ 81.7	$ 612.7	$ 1,427.0	$ (161.3)	$ (47.8)	$ 1,912.3
Beginning Balance, Shares at Dec. 31, 2008		81,700,000				(2,300,000)
Net income (loss)	(137.7)			(137.7)			(137.7)
Other comprehensive income (loss), net of tax:
Change in funded status of pension liability	35.6				35.6		35.6
Unrealized loss on derivative financial instruments	27.8				27.8		27.8
Other changes	(0.1)				(0.1)		(0.1)
Comprehensive net income	(74.4)						(74.4)
Cash dividends on common stock	(25.3)			(25.3)			(25.3)
Restricted shares issued, net			(12.6)			12.6
Restricted shares issued, net, Shares						500,000
Shares repurchased, value	(6.3)					(6.3)	(6.3)
Shares repurchased, shares						(800,000)
Stock options exercised	1.1		(0.6)			1.7	1.1
Stock options exercised, Shares						100,000
Income tax expense from stock options exercised	(2.1)		(2.1)				(2.1)
Stock-based compensation expense	1.0		1.0				1.0
Other				(0.1)		0.1
Ending Balance at Dec. 31, 2009 (Previously Reported)	1,806.3	81.7	598.4	1,263.9	(98.0)	(39.7)	1,806.3
Ending Balance at Dec. 31, 2009	1,830.8	81.7	598.4	1,158.5	(98.0)	(39.7)	1,700.9	129.9
Ending Balance, Shares at Dec. 31, 2009 (Previously Reported)		81,700,000				(2,500,000)
Ending Balance, Shares at Dec. 31, 2009		81,700,000				(2,500,000)
Net income (loss)	75.4			67.4			67.4	8.0
Other comprehensive income (loss), net of tax:
Change in funded status of pension liability	8.7				8.7		8.7
Unrealized loss on derivative financial instruments	(16.4)				(7.3)		(7.3)	(9.1)
Other changes	1.1				1.1		1.1
Comprehensive net income	68.8						69.9	(1.1)
Cumulative effect of consolidating TRIP Holdings	24.5			(105.4)			(105.4)	129.9
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 from stock options exercised	(0.2)		(0.2)				(0.2)
Stock-based compensation expense	0.6		0.6				0.6
Reclassification of purchase of additional interest in TRIP Holdings	(37.6)		10.3				10.3	(47.9)
Other	0.1		0.1			0.1	0.1
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)
Net income (loss)	145.7			142.2			142.2	3.5
Other comprehensive income (loss), net of tax:
Change in funded status of pension liability	(28.6)				(28.6)		(28.6)
Unrealized loss on derivative financial instruments	0.2				0.1		0.1	0.1
Comprehensive net income	117.3						113.7	3.6
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	226,571					200,000
Income tax expense from stock options exercised	3.5		3.5				3.5
Stock-based compensation expense	0.6		0.6				0.6
Reclassification of purchase of additional interest in TRIP Holdings			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)