Derivative Instruments (Details 1) (Designated as hedging instrument, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Expired hedges | TRIP Holdings warehouse loan
Effect on interest expense - increase/(decrease)
Expected effect during next twelve months	$ 4.9
Interest expense | Expired hedges | 2006 secured railcar equipment notes
Effect on interest expense - increase/(decrease)
Effect on interest expense	(0.1)		(0.1)
Expected effect during next twelve months	(0.3)	[1]
Interest expense | Expired hedges | Promissory notes
Effect on interest expense - increase/(decrease)
Effect on interest expense	0.7		0.8
Expected effect during next twelve months	0.5	[1]
Interest expense | Expired hedges | TRIP Holdings warehouse loan
Effect on interest expense - increase/(decrease)
Effect on interest expense	1.3		1.3
Expected effect during next twelve months	4.9	[1]
Interest expense | Open hedges | Promissory notes
Effect on interest expense - increase/(decrease)
Effect on interest expense	3.7		3.9
Expected effect during next twelve months	2.5	[1]
Interest expense | Open hedges | TRIP Master Funding secured railcar equipment notes
Effect on interest expense - increase/(decrease)
Effect on interest expense	0.3		0.4
Expected effect during next twelve months	$ 1.1	[1]

[1] Based on the fair value of open hedges as of March 31, 2015