Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (131.3)			$ (128.4)
Other comprehensive income before reclassifications	10.2			5.9
Reclassifications [Abstract]
Total other comprehensive income	11.5		6.9	8.6		(10.3)
Ending balance	(119.8)			(119.8)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.5	[1]		3.1	[1]
Amortization of unrecognized prior service credit	(0.3)	[1]		(0.6)	[1]
Commodity derivatives	0.1	[2]		0.2	[2]
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	13.5			17.8
Other comprehensive income before reclassifications	10.2			5.9
Reclassifications [Abstract]
Total other comprehensive income	10.2			5.9
Ending balance	23.7			23.7
Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	0	[1]		0	[1]
Amortization of unrecognized prior service credit	0	[1]		0	[1]
Commodity derivatives	0	[2]		0	[2]
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1.0)			(1.1)
Other comprehensive income before reclassifications	0			0
Reclassifications [Abstract]
Total other comprehensive income	0.1			0.2
Ending balance	(0.9)			(0.9)
Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	0	[1]		0	[1]
Amortization of unrecognized prior service credit	0	[1]		0	[1]
Commodity derivatives	0.1	[2]		0.2	[2]
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(143.8)			(145.1)
Other comprehensive income before reclassifications	0			0
Reclassifications [Abstract]
Total other comprehensive income	1.2			2.5
Ending balance	(142.6)			(142.6)
Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.5	[1]		3.1	[1]
Amortization of unrecognized prior service credit	(0.3)	[1]		(0.6)	[1]
Commodity derivatives	$ 0	[2]		$ 0	[2]

[1] Amounts are included in the calculation of net periodic benefit cost. See Note 5 for additional information.

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