Basis of Presentation Basis of Presentation (non-printing) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended					12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Service Life [Member]	Jun. 30, 2014 Railcars [Member] Service Life [Member]	Jun. 30, 2014 Railcars [Member] Minimum [Member]	Jun. 30, 2014 Railcars [Member] Minimum [Member] Service Life [Member]	Jun. 30, 2014 Railcars [Member] Maximum [Member]	Jun. 30, 2014 Railcars [Member] Maximum [Member] Service Life [Member]	Dec. 31, 2014 Scenario, Forecast [Member] Service Life [Member]
Change in Accounting Estimate [Line Items]
Change in accounting estimate					$ 3.5						$ 14.0
Property, Plant and Equipment, Useful Life							30 years	27 years	38 years	42 years
Average Increase (Decrease) in Estimated Railcar Useful Life						2 years 2 months 12 days
Depreciation, Nonproduction			136.5	127.2	0						21.9
Net Income (Loss) Attributable to Parent	$ 53.1	$ 35.1	$ 95.2	$ 62.2
Earnings Per Share, Diluted	$ 1.15	$ 0.74	$ 2.05	$ 1.31
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share					$ 0.08						$ 0.30