Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Other comprehensive income (Loss) [Abstract]
Beginning balance		$ 490.1
Other comprehensive income (loss) before reclassifications		(24.2)	$ 16.5
Reclassifications for amortization of unrecognized net loss	[1]	1.3	1.3
Income taxes		(0.4)	(0.5)
Total other comprehensive income (loss)		(23.3)	17.3
Ending balance		479.5
Accumulated Other Comprehensive Loss [Member]
Other comprehensive income (Loss) [Abstract]
Beginning balance		(140.3)	(181.8)
Ending balance		(163.6)	(164.5)
Foreign Currency Translation [Member]
Other comprehensive income (Loss) [Abstract]
Beginning balance		(5.5)	(46.8)
Other comprehensive income (loss) before reclassifications		(24.7)	16.5
Reclassifications for amortization of unrecognized net loss	[1]	0.0	0.0
Income taxes		0.0	0.0
Total other comprehensive income (loss)		(24.7)	16.5
Ending balance		(30.2)	(30.3)
Defined Benefit Plans [Member]
Other comprehensive income (Loss) [Abstract]
Beginning balance		(134.9)	(135.0)
Other comprehensive income (loss) before reclassifications		0.0	0.0
Reclassifications for amortization of unrecognized net loss	[1]	1.3	1.3
Income taxes		(0.3)	(0.5)
Total other comprehensive income (loss)		1.0	0.8
Ending balance		(133.9)	$ (134.2)
Cash Flow Hedges [Member]
Other comprehensive income (Loss) [Abstract]
Beginning balance		0.1
Other comprehensive income (loss) before reclassifications		0.5
Reclassifications for amortization of unrecognized net loss	[1]	0.0
Income taxes		(0.1)
Total other comprehensive income (loss)		0.4
Ending balance		$ 0.5

[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.