Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		12 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		$ (198.6)	$ (103.9)
Other comprehensive loss before reclassifications		(11.9)	(113.2)
Reclassifications [Abstract]
Income taxes		(11.8)	13.2
Total other comprehensive loss		24.4	(94.7)
Ending balance		(174.2)	(198.6)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	[1]	48.3	5.4
Amortization of unrecognized prior service credit	[1]	(0.2)	(0.1)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(40.7)	27.3
Other comprehensive loss before reclassifications		4.7	(68.0)
Reclassifications [Abstract]
Income taxes		0.0	0.0
Total other comprehensive loss		4.7	(68.0)
Ending balance		(36.0)	(40.7)
Foreign Currency Translation [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	[1]	0.0	0.0
Amortization of unrecognized prior service credit	[1]	0.0	0.0
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(157.9)	(131.2)
Other comprehensive loss before reclassifications		(16.6)	(45.2)
Reclassifications [Abstract]
Income taxes		(11.8)	13.2
Total other comprehensive loss		19.7	(26.7)
Ending balance		(138.2)	(157.9)
Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassifications [Abstract]
Amortization of unrecognized net loss	[1]	48.3	5.4
Amortization of unrecognized prior service credit	[1]	$ (0.2)	$ (0.1)

[1] Amounts are included in the calculation of net periodic benefit cost for the Company's defined benefit plans, which include pension and other postretirement plans. See Note 17 for additional information about the Company's pension plans.