Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Designated as hedging instrument Expired hedges 2006 secured railcar equipment notes		Dec. 31, 2012 Designated as hedging instrument Expired hedges Promissory notes		Dec. 31, 2012 Designated as hedging instrument Expired hedges TRIP Holdings		Dec. 31, 2012 Designated as hedging instrument Open hedges Promissory notes		Dec. 31, 2012 Designated as hedging instrument Open hedges TRIP Master Funding secured railcar equipment notes		Jul. 31, 2011 Designated as hedging instrument Open hedges TRIP Master Funding secured railcar equipment notes
Interest rate hedges included in balance sheet
Notional Amount					$ 200.0		$ 370.0		$ 788.5		$ 443.8		$ 78.4		$ 94.1
Interest Rate					4.87%	[1]	5.34%	[1]	3.60%	[1]	4.13%	[1]	2.62%	[1]
Liability					0		0		0		37.6		5.2
AOCL - loss/(income)	34.8	46.2	36.3	29.0	(1.9)		7.2		19.9		34.9		2.9
Noncontrolling Interest					$ 0		$ 0		$ 14.9		$ 0		$ 2.2

[1] Weighted average fixed interest rate