Accounting Changes Accounting Changes (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Depreciation, Nonproduction		$ 290.5	$ 273.5	$ 255.0
Unamortized Debt Issuance Expense	$ 17.6	$ 18.8	17.6
Service Life [Member]
Property, Plant and Equipment [Line Items]
Depreciation, Nonproduction	$ 21.9
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income			$ 14.0
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Diluted Earnings Per Share			$ 0.31
Railcars [Member]
Property, Plant and Equipment [Line Items]
Average Increase (Decrease) in Estimated Railcar Useful Life			2 years 2 months 12 days
Railcars [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		20 years	27 years	30 years
Railcars [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		42 years	42 years	38 years