Derivative Instruments (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014	Jul. 31, 2011
Interest rate hedges included in balance sheet
AOCL – loss/ (income)		$ 2.0	$ 6.6
Designated as hedging instrument | Expired hedges | 2006 secured railcar equipment notes
Interest rate hedges included in balance sheet
Notional Amount		$ 200.0
Interest Rate	[1]	4.87%
Liability		$ 0.0
AOCL – loss/ (income)		(1.2)
Noncontrolling Interest		0.0
Designated as hedging instrument | Expired hedges | Promissory notes
Interest rate hedges included in balance sheet
Notional Amount		370.0
Designated as hedging instrument | Expired hedges | TRIP Holdings warehouse loan
Interest rate hedges included in balance sheet
Notional Amount		$ 788.5
Interest Rate	[1]	3.60%
Liability		$ 0.0
AOCL – loss/ (income)		9.0
Noncontrolling Interest		12.1
Designated as hedging instrument | Open hedge | TRIP Master Funding secured railcar equipment notes
Interest rate hedges included in balance sheet
Notional Amount		$ 51.2		$ 94.1
Interest Rate	[1]	2.62%
Liability		$ 1.9
AOCL – loss/ (income)		0.8
Noncontrolling Interest		$ 1.0

[1] Weighted average fixed interest rate