Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2014		Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (124.9)		$ (119.8)		$ (103.9)		$ (128.4)
Other comprehensive income before reclassifications	(15.1)		0.9		(37.9)		6.8
Reclassifications [Abstract]
Total other comprehensive (loss) income	(14.3)		2.3		(35.3)		10.9
Ending balance	(139.2)		(117.5)		(139.2)		(117.5)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.3	[1]	1.6	[1]	4.0	[1]	4.7	[1]
Amortization of unrecognized prior service credit			(0.3)	[1]			(0.9)	[1]
Commodity derivatives			0.1	[2]			0.3	[2]
Income taxes	(0.5)				(1.4)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	4.5		23.7		27.3		17.8
Other comprehensive income before reclassifications	(15.1)		0.9		(37.9)		6.8
Reclassifications [Abstract]
Total other comprehensive (loss) income	(15.1)		0.9		(37.9)		6.8
Ending balance	(10.6)		(24.6)		(10.6)		(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]	0	[1]	0	[1]
Amortization of unrecognized prior service credit			0	[1]			0	[1]
Commodity derivatives			0	[2]			0	[2]
Income taxes	0				0
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	0		(0.9)		0		(1.1)
Other comprehensive income before reclassifications	0		0		0		0
Reclassifications [Abstract]
Total other comprehensive (loss) income	0		0.1		0		0.3
Ending balance	0		(0.8)		0		(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]	0	[1]	0	[1]
Amortization of unrecognized prior service credit			0	[1]			0	[1]
Commodity derivatives			0.1	[2]			0.3	[2]
Income taxes	0				0
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(129.4)		(142.6)		(131.2)		(145.1)
Other comprehensive income before reclassifications	0		0		0		0
Reclassifications [Abstract]
Total other comprehensive (loss) income	0.8		1.3		2.6		3.8
Ending balance	(128.6)		(141.3)		(128.6)		(141.3)
Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	1.3	[1]	1.6	[1]	4.0	[1]	4.7	[1]
Amortization of unrecognized prior service credit			(0.3)	[1]			(0.9)	[1]
Commodity derivatives			0	[2]			0	[2]
Income taxes	$ (0.5)				$ (1.4)

[1] Amounts are included in the calculation of net periodic benefit cost. See Note 4 for additional information.

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