Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Other comprehensive loss [Abstract]
Beginning balance						$ 533.9
Other comprehensive loss before reclassifications		$ (19.3)		$ (6.8)		(18.4)		$ (31.0)
Reclassifications for amortization of unrecognized net loss	[1]	1.4		1.3		2.8		2.6
Reclassifications for realized losses - net	[2]	0.3				0.2
Reclassifications for foreign currency translation gains (losses)		(0.6)	[3]	0.8	[4]	(0.6)	[3]	0.8	[4]
Income taxes		(0.2)		(0.1)		(0.2)		(0.5)
Total other comprehensive income (loss)		(18.4)		(4.8)		(16.2)		(28.1)
Ending balance		519.9				519.9
AIAC Air Conditioning South Africa Pty Ltd Member [Member]
Other comprehensive loss [Abstract]
Gain (loss) on write-off of accumulated foreign currency translation				(0.8)
Nikkei Heat Exchanger Company, Ltd [Member]
Other comprehensive loss [Abstract]
Gain (loss) on write-off of accumulated foreign currency translation		0.6
Accumulated Other Comprehensive Loss [Member]
Other comprehensive loss [Abstract]
Beginning balance		(176.2)		(163.6)		(178.4)		(140.3)
Ending balance		(194.6)		(168.4)		(194.6)		(168.4)
Foreign Currency Translation [Member]
Other comprehensive loss [Abstract]
Beginning balance		(40.7)		(30.2)		(42.6)		(5.5)
Other comprehensive loss before reclassifications		(18.7)		(6.1)		(16.8)		(30.8)
Reclassifications for amortization of unrecognized net loss	[1]	0.0		0.0		0.0		0.0
Reclassifications for realized losses - net	[2]	0.0				0.0
Reclassifications for foreign currency translation gains (losses)		(0.6)	[3]	0.8	[4]	(0.6)	[3]	0.8	[4]
Income taxes		0.0		0.0		0.0		0.0
Total other comprehensive income (loss)		(19.3)		(5.3)		(17.4)		(30.0)
Ending balance		(60.0)		(35.5)		(60.0)		(35.5)
Defined Benefit Plans [Member]
Other comprehensive loss [Abstract]
Beginning balance		(135.2)		(133.9)		(136.3)		(134.9)
Other comprehensive loss before reclassifications		0.0		0.0		0.0		0.0
Reclassifications for amortization of unrecognized net loss	[1]	1.4		1.3		2.8		2.6
Reclassifications for realized losses - net	[2]	0.0				0.0
Reclassifications for foreign currency translation gains (losses)		0.0	[3]	0.0	[4]	0.0	[3]	0.0	[4]
Income taxes		(0.3)		(0.3)		(0.6)		(0.6)
Total other comprehensive income (loss)		1.1		1.0		2.2		2.0
Ending balance		(134.1)		(132.9)		(134.1)		(132.9)
Cash Flow Hedges [Member]
Other comprehensive loss [Abstract]
Beginning balance		(0.3)		0.5		0.5		0.1
Other comprehensive loss before reclassifications		(0.6)		(0.7)		(1.6)		(0.2)
Reclassifications for amortization of unrecognized net loss	[1]	0.0		0.0		0.0		0.0
Reclassifications for realized losses - net	[2]	0.3				0.2
Reclassifications for foreign currency translation gains (losses)		0.0	[3]	0.0	[4]	0.0	[3]	0.0	[4]
Income taxes		0.1		0.2		0.4		0.1
Total other comprehensive income (loss)		(0.2)		(0.5)		(1.0)		(0.1)
Ending balance		$ (0.5)		$ 0.0		$ (0.5)		$ 0.0

[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.

[2] Amounts represent net gains and losses associated with cash flow hedges that were reclassified to net earnings.

[3] As a result of the sale of its investment in NEX during the second quarter of fiscal 2020, the Company wrote off $0.6 million of accumulated foreign currency translation gains.

[4] As a result of the sale of a business in South Africa during the second quarter of fiscal 2019, the Company wrote off $0.8 million of accumulated foreign currency translation losses.