Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2013		Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (119.8)			$ (128.4)
Other comprehensive income before reclassifications	0.9			6.8
Reclassifications [Abstract]
Total other comprehensive income	2.3		5.2	10.9		(5.2)
Ending balance	(117.5)			(117.5)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.6	[1]		4.7	[1]
Amortization of unrecognized prior service credit	(0.3)	[1]		(0.9)	[1]
Commodity derivatives	0.1	[2]		0.3	[2]
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	23.7			17.8
Other comprehensive income before reclassifications	0.9			6.8
Reclassifications [Abstract]
Total other comprehensive income	0.9			6.8
Ending balance	24.6			24.6
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	(0.9)			(1.1)
Other comprehensive income before reclassifications	0			0
Reclassifications [Abstract]
Total other comprehensive income	0.1			0.3
Ending balance	(0.8)			(0.8)
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]		0.3	[2]
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(142.6)			(145.1)
Other comprehensive income before reclassifications	0			0
Reclassifications [Abstract]
Total other comprehensive income	1.3			3.8
Ending balance	(141.3)			(141.3)
Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.6	[1]		4.7	[1]
Amortization of unrecognized prior service credit	(0.3)	[1]		(0.9)	[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.