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, 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			81,700,000				(2,600,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	273.1				262.7			262.7	10.4
Other comprehensive income	16.4					13.2		13.2	3.2
Cash dividends on common stock	(30.5)				(30.5)			(30.5)
Restricted shares, net	24.0			10.6			13.4	24.0
Restricted shares, net, Shares							700,000
Shares repurchased	(73.8)						(73.8)	(73.8)
Shares repurchased, Shares	(1,834,189)						(1,800,000)
Stock options exercised	2.1			(1.8)			3.9	2.1
Stock options exercised, Shares							100,000
Excess tax benefits from stock-based compensation	8.3			8.3				8.3
Repurchase of interests in partially-owned leasing subsidiary	(84.2)			11.8		(11.8)		0	(84.2)
Sale of interests in partially-owned leasing subsidiaries	291.3			(7.3)		13.2		5.9	285.4
Contributions from noncontrolling interest	50.0								50.0
Distributions to noncontrolling interest	(3.3)								(3.3)
Other	(0.5)			(0.5)				(0.5)
Ending balance at Sep. 30, 2013	$ 2,610.5	[1]	$ 81.7	$ 673.7	$ 1,768.9	$ (135.5)	$ (124.4)	$ 2,264.4	$ 346.1
Ending balance, Shares at Sep. 30, 2013			81,700,000				(3,600,000)

[1] (unaudited)