Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance				$ 414.0
Other comprehensive income (loss) before reclassifications		$ 5.2	$ (14.2)	33.0	$ (17.2)
Reclassifications for amortization of unrecognized net loss	[1]	1.3	1.3	3.9	3.9
Income taxes		(0.6)	(0.4)	(1.5)	(1.3)
Total other comprehensive income (loss)		5.9	(13.3)	35.4	(14.6)
Ending balance		463.7		463.7
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(152.3)	(175.5)	(181.8)	(174.2)
Ending balance		(146.4)	(188.8)	(146.4)	(188.8)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(19.0)	(39.0)	(46.8)	(36.0)
Other comprehensive income (loss) before reclassifications		4.6	(14.2)	32.4	(17.2)
Reclassifications for amortization of unrecognized net loss	[1]	0.0	0.0	0.0	0.0
Income taxes		0.0	0.0	0.0	0.0
Total other comprehensive income (loss)		4.6	(14.2)	32.4	(17.2)
Ending balance		(14.4)	(53.2)	(14.4)	(53.2)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		0.0		0.0
Other comprehensive income (loss) before reclassifications		0.6		0.6
Reclassifications for amortization of unrecognized net loss	[1]	0.0		0.0
Income taxes		(0.2)		(0.2)
Total other comprehensive income (loss)		0.4		0.4
Ending balance		0.4		0.4
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance		(133.3)	(136.5)	(135.0)	(138.2)
Other comprehensive income (loss) before reclassifications		0.0	0.0	0.0	0.0
Reclassifications for amortization of unrecognized net loss	[1]	1.3	1.3	3.9	3.9
Income taxes		(0.4)	(0.4)	(1.3)	(1.3)
Total other comprehensive income (loss)		0.9	0.9	2.6	2.6
Ending balance		$ (132.4)	$ (135.6)	$ (132.4)	$ (135.6)

[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.