Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Interest Rate Locks, 2005 to 2006 [Member]	Dec. 31, 2011 Interest Rate Locks, 2006 to 2007 [Member]	Dec. 31, 2011 Interest Rate Swap, 2008 Debt Issuance [Member]	Dec. 31, 2011 Interest Rate Swap TRIP Rail Master Funding Secured Railcar Equipment Notes [Member]	Jul. 31, 2011 Interest Rate Swap TRIP Rail Master Funding Secured Railcar Equipment Notes [Member]	Dec. 31, 2011 Interest Rate Locks, TRIP Holdings [Member]
Interest rate hedges included in balance sheet
Notional Amount			$ 200.0	$ 370.0	$ 474.7	$ 89.5	$ 94.1	$ 788.5
Interest Rate			4.87%	5.34%	4.13%	2.62%		3.60%
Liability					48.9	4.8
AOCL loss/(income)	(46.2)	(36.3)	(2.3)	10.6	46.7	2.7		23.4
Noncontrolling Interest						$ 2.0		$ 17.5