Derivative Instruments, (Gain) Loss by Hedging Relationship, by Income Statement Location (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Derivative Instruments, (Gain) Loss [Line Items]
Amount of Loss (Gain) Recognized in AOCI	$ 0.5	$ 3.1	$ (0.3)
Loss Reclassified from AOCI into Continuing Operations	2.6	3.1	1.8
Total Loss (Gain) Recognized in Continuing Operations	4.3	3.4	1.8
Cost of Sales [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Loss recognized in AOCI expected to reclassify from AOCI to cost of sales during next twelve months	0.4
Cost of Sales [Member] | Commodity Derivatives [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Amount of Loss (Gain) Recognized in AOCI	0.5	3.1	(0.3)
Statement of Operations Location	Cost of sales	Cost of sales	Cost of sales
Loss Reclassified from AOCI into Continuing Operations	2.6	3.1	0
Total Loss (Gain) Recognized in Continuing Operations	4.6	3.0	0
Other Expense - net [Member] | Foreign Exchange Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Amount of Loss (Gain) Recognized in AOCI	0	0
Statement of Operations Location	Other expense - net	Other expense - net
Loss Reclassified from AOCI into Continuing Operations	0	0
Total Loss (Gain) Recognized in Continuing Operations	(0.3)	0.4
Interest Expense [Member] | Interest Rate Derivative [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Amount of Loss (Gain) Recognized in AOCI			0
Statement of Operations Location			Interest expense
Loss Reclassified from AOCI into Continuing Operations			1.8
Total Loss (Gain) Recognized in Continuing Operations			$ 1.8