Derivative Instruments (Details 1) (Designated as hedging instrument, USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Expired hedges | 2006 secured railcar equipment notes
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)	[1]		(0.3)	[1]
Expired hedges | Promissory notes
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	0.8		0.8	1.6		1.7
Expected effect during next twelve months	3.0	[1]		3.0	[1]
Expired hedges | TRIP Holdings warehouse loan
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	1.5		1.5	3.5		3.0
Expected effect during next twelve months	5.2	[1]		5.2	[1]
Open hedges | Promissory notes
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	4.1		4.2	8.0		8.4
Expected effect during next twelve months	16.1	[1]		16.1	[1]
Open hedges | TRIP Master Funding secured railcar equipment notes
Interest rate hedges effect on interest expense - increase/(decrease)
Effect on interest expense - increase/(decrease)	0.4		0.5	0.9		1.0
Expected effect during next twelve months	$ 1.6	[1]		$ 1.6	[1]

[1] Based on the fair value of open hedges as of June 30, 2013