Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		12 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Changes in Accumulated Other Comprehensive Loss [Abstract]
Beginning balance		$ 487.9
Other comprehensive income (loss) before reclassifications		66.3	$ (59.4)
Reclassifications for amortization of unrecognized net loss	[1]	6.7	5.8
Reclassifications for realized losses - net	[2]	0.1	0.5
Reclassifications for foreign currency translation gains	[3]		(0.6)
Income taxes		(11.0)	8.8
Total other comprehensive income (loss)		62.1	(44.9)
Ending balance		348.7	487.9
Nikkei Heat Exchanger Company, Ltd [Member]
Changes in Accumulated Other Comprehensive Loss [Abstract]
Gain (loss) on write-off of accumulated foreign currency translation			0.6
Accumulated Other Comprehensive Loss [Member]
Changes in Accumulated Other Comprehensive Loss [Abstract]
Beginning balance		(223.3)	(178.4)
Ending balance		(161.2)	(223.3)
Foreign Currency Translation [Member]
Changes in Accumulated Other Comprehensive Loss [Abstract]
Beginning balance		(61.4)	(42.6)
Other comprehensive income (loss) before reclassifications		30.4	(18.2)
Reclassifications for amortization of unrecognized net loss	[1]	0.0	0.0
Reclassifications for realized losses - net	[2]	0.0	0.0
Reclassifications for foreign currency translation gains	[3]		(0.6)
Income taxes		0.0	0.0
Total other comprehensive income (loss)		30.4	(18.8)
Ending balance		(31.0)	(61.4)
Defined Benefit Plans [Member]
Changes in Accumulated Other Comprehensive Loss [Abstract]
Beginning balance		(160.9)	(136.3)
Other comprehensive income (loss) before reclassifications		33.8	(38.7)
Reclassifications for amortization of unrecognized net loss	[1]	6.7	5.8
Reclassifications for realized losses - net	[2]	0.0	0.0
Reclassifications for foreign currency translation gains	[3]		0.0
Income taxes		(10.4)	8.3
Total other comprehensive income (loss)		30.1	(24.6)
Ending balance		(130.8)	(160.9)
Cash Flow Hedges [Member]
Changes in Accumulated Other Comprehensive Loss [Abstract]
Beginning balance		(1.0)	0.5
Other comprehensive income (loss) before reclassifications		2.1	(2.5)
Reclassifications for amortization of unrecognized net loss	[1]	0.0	0.0
Reclassifications for realized losses - net	[2]	0.1	0.5
Reclassifications for foreign currency translation gains	[3]		0.0
Income taxes		(0.6)	0.5
Total other comprehensive income (loss)		1.6	(1.5)
Ending balance		$ 0.6	$ (1.0)

[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 18 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. See Note 19 for additional information regarding derivative instruments.

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