Debt (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Operating assets pledged as collateral for notes	$ 606.7
Expiry of registration statement	August 2013
Fixed charge coverage ratio	1.8
Minimum debt covenant fixed charge coverage ratio	1.2
Amount of secured debt available to be borrowed in accordance with public debt covenants	918.6
Line of Credit US [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	560.0
Maturity date of revolving credit facility	May 31, 2015
Availability under credit facility	365.3
Commercial paper	185.0
Letter of credit issued	9.7
Annual commitment fees	1.2	0.9	0.4
Line of Credit Europe [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility	112.1
Availability under credit facility	23.5
Maximum amount of GRE transfer to GATX relating to loans and dividends	81.4
Restricted net assets	$ 389.7