Consolidated Statement of Stockholders' Equity (unaudited) - 9 months ended Sep. 30, 2015 - USD ($) $ in Millions	Total		Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Trinity Stockholders' Equity	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2014			155,700,000				100,000
Beginning balance at Dec. 31, 2014	$ 3,397.4		$ 155.7	$ 463.2	$ 2,489.9	$ (111.9)	$ (1.0)	$ 2,995.9	$ 401.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	622.0				596.5			596.5	25.5
Other comprehensive income	4.0					2.0		2.0	2.0
Cash dividends on common stock	(49.2)				(49.2)			(49.2)
Restricted shares, net, (in shares)			2,100,000				1,000,000
Restricted shares, net	$ 18.9		$ 0.0	49.2			$ (30.3)	18.9
Shares repurchased (in shares)	(3,947,320)						(3,900,000)
Shares repurchased	$ (115.0)						$ (115.0)	(115.0)
Stock options exercised (in shares)			0
Stock options exercised	0.2		$ 0.0	0.2				0.2
Excess tax benefits from stock-based compensation	12.4			12.4				12.4
Distributions to noncontrolling interest	(30.4)							0.0	(30.4)
Retirement of treasury stock (in shares)			(3,300,000)				(3,300,000)
Retirement of treasury stock	0.0		$ 0.0	(103.4)			$ (103.4)	0.0
Change in par value of common stock	0.0		$ (154.2)	154.2				0.0
Ending balance (in shares) at Sep. 30, 2015			154,500,000				1,700,000
Ending balance at Sep. 30, 2015	$ 3,860.3	[1]	$ 1.5	$ 575.8	$ 3,037.2	$ (109.9)	$ (42.9)	$ 3,461.7	$ 398.6

[1] (unaudited)