Derivative Instruments (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Interest Rate Locks, 2005 to 2006 [Member]
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	$ (0.1)	$ (0.1)	$ (0.2)	$ (0.2)
Expected effect during next twelve months	(0.3)		(0.3)
Interest Rate Locks, 2006 to 2007 [Member]
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	0.8	0.9	1.7	1.8
Expected effect during next twelve months	3.3		3.3
Interest Rate Locks, TRIP Holdings [Member]
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	1.5		3.0
Expected effect during next twelve months	5.9		5.9
Trip Warehouse [Member]
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)		6.8		14.1
Interest Rate Swap TRIP Master Funding Secured Railcar Equipment Notes [Member]
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	0.5		1.0
Expected effect during next twelve months	1.7		1.7
Interest Rate Swap, 2008 Debt Issuance [Member]
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	4.2	5.2	8.4	9.7
Expected effect during next twelve months	$ 16.9		$ 16.9