Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2011 Interest Rate Derivative [Member]	Mar. 31, 2013 Commodity Derivatives [Member] Designated as Cash Flow Hedges [Member] Other current assets [Member]	Mar. 31, 2012 Commodity Derivatives [Member] Designated as Cash Flow Hedges [Member] Other current assets [Member]	Mar. 31, 2013 Commodity Derivatives [Member] Designated as Cash Flow Hedges [Member] Other current liabilities [Member]	Mar. 31, 2012 Commodity Derivatives [Member] Designated as Cash Flow Hedges [Member] Other current liabilities [Member]	Mar. 31, 2013 Commodity Derivatives [Member] Not Designated as Hedges [Member] Other current liabilities [Member]	Mar. 31, 2012 Commodity Derivatives [Member] Not Designated as Hedges [Member] Other current liabilities [Member]	Mar. 31, 2013 Commodity Derivatives [Member] Not Designated as Hedges [Member] Other noncurrent liabilities [Member]	Mar. 31, 2012 Commodity Derivatives [Member] Not Designated as Hedges [Member] Other noncurrent liabilities [Member]	Mar. 31, 2013 Foreign Exchange Contracts [Member] Not Designated as Hedges [Member] Other current assets [Member]	Mar. 31, 2012 Foreign Exchange Contracts [Member] Not Designated as Hedges [Member] Other current assets [Member]
Derivative, Fair Value, Net [Abstract]
Unamortized balance of interest rate derivatives reflected as component of interest expense	$ 1.6
Derivative Asset, Fair Value, Net		0	0.2							0	0.2
Derivative Liability, Fair Value, Net				$ 0	$ 0.9	$ 1.2	$ 2.6	$ 0.1	$ 0