Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2013		Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (128.4)
Other comprehensive loss before reclassifications	(4.3)
Reclassifications [Abstract]
Total other comprehensive (loss) income	(2.9)		(17.2)
Ending balance	(131.3)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.6	[1]
Amortization of unrecognized prior service credit	(0.3)	[1]
Commodity derivatives	0.1	[2]
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	17.8
Other comprehensive loss before reclassifications	(4.3)
Reclassifications [Abstract]
Total other comprehensive (loss) income	(4.3)
Ending balance	13.5
Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	0	[1]
Amortization of unrecognized prior service credit	0	[1]
Commodity derivatives	0	[2]
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1.1)
Other comprehensive loss before reclassifications	0
Reclassifications [Abstract]
Total other comprehensive (loss) income	0.1
Ending balance	(1.0)
Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	0	[1]
Amortization of unrecognized prior service credit	0	[1]
Commodity derivatives	0.1	[2]
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(145.1)
Other comprehensive loss before reclassifications	0
Reclassifications [Abstract]
Total other comprehensive (loss) income	1.3
Ending balance	(143.8)
Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.6	[1]
Amortization of unrecognized prior service credit	(0.3)	[1]
Commodity derivatives	$ 0	[2]

[1] Amounts are included in the calculation of net periodic benefit cost. See Note 3 for additional information.

[2] Reclassifications for commodity derivatives are included in cost of sales.