Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance				$ 376.2
Other comprehensive income (loss) before reclassifications		$ (14.2)	$ (4.0)	(17.2)	$ (13.3)
Reclassifications [Abstract]
Amortization of unrecognized net loss	[1]	1.3	2.5	3.9	45.3
Amortization of unrecognized prior service credit	[1]		(0.1)		(0.2)
Income taxes		(0.4)	(1.7)	(1.3)	(14.3)
Total other comprehensive income (loss)		(13.3)	(3.3)	(14.6)	17.5
Ending balance		397.8		397.8
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(175.5)	(177.8)	(174.2)	(198.6)
Reclassifications [Abstract]
Ending balance		(188.8)	(181.1)	(188.8)	(181.1)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(39.0)	(40.3)	(36.0)	(40.7)
Other comprehensive income (loss) before reclassifications		(14.2)	(6.2)	(17.2)	(5.8)
Reclassifications [Abstract]
Amortization of unrecognized net loss	[1]	0.0	0.0	0.0	0.0
Amortization of unrecognized prior service credit	[1]		0.0		0.0
Income taxes		0.0	0.0	0.0	0.0
Total other comprehensive income (loss)		(14.2)	(6.2)	(17.2)	(5.8)
Ending balance		(53.2)	(46.5)	(53.2)	(46.5)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(136.5)	(137.5)	(138.2)	(157.9)
Other comprehensive income (loss) before reclassifications		0.0	2.2	0.0	(7.5)
Reclassifications [Abstract]
Amortization of unrecognized net loss	[1]	1.3	2.5	3.9	45.3
Amortization of unrecognized prior service credit	[1]		(0.1)		(0.2)
Income taxes		(0.4)	(1.7)	(1.3)	(14.3)
Total other comprehensive income (loss)		0.9	2.9	2.6	23.3
Ending balance		$ (135.6)	$ (134.6)	$ (135.6)	$ (134.6)

[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 4 for additional information about the Company's pension plans.