Consolidated Statement of Stockholders' Equity (USD $) In Millions, 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, 2012	$ 2,137.6		$ 81.7	$ 652.6	$ 1,536.7	$ (150.1)	$ (67.9)	$ 2,053.0	$ 84.6
Beginning balance, Shares at Dec. 31, 2012			81.7				(2.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	78.8				79.1			79.1	(0.3)
Other comprehensive income	4.6					3.9		3.9	0.7
Cash dividends on common stock	(8.7)				(8.7)			(8.7)
Restricted shares, net	8.8			7.0			1.8	8.8
Restricted shares, net, Shares							0
Stock options exercised	1.4			(1.4)			2.8	1.4
Stock options exercised, Shares							0.1
Excess tax benefits from stock-based compensation	0.6			0.6				0.6
Purchase of additional interest in partially-owned leasing subsidiary	(31.9)			2.9		(2.5)		0.4	(32.3)
Ending balance at Mar. 31, 2013	$ 2,191.2	[1]	$ 81.7	$ 661.7	$ 1,607.1	$ (148.7)	$ (63.3)	$ 2,138.5	$ 52.7
Ending balance, Shares at Mar. 31, 2013			81.7				(2.5)

[1] (unaudited)