Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Other comprehensive loss [Abstract]
Beginning balance					$ 487.9
Other comprehensive income (loss) before reclassifications		$ 18.4	$ 14.1		42.1	$ (4.3)
Reclassifications for amortization of unrecognized net loss	[1]	1.6	1.4		4.9	4.2
Reclassifications for realized (gains) losses - net	[2]	(0.4)	0.5		0.4	0.7
Foreign currency translation gains			0.0			(0.6)	[3]
Income taxes		(0.3)	(0.6)		(1.6)	(0.8)
Total other comprehensive income (loss)		19.3	15.4		45.8	(0.8)
Ending balance		341.5			341.5
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		(196.8)	(194.6)		(223.3)	(178.4)
Ending balance		(177.5)	(179.2)	(194.6)	(177.5)	(179.2)
Foreign Currency Translation [Member]
Other comprehensive loss [Abstract]
Beginning balance		(38.8)	(60.0)		(61.4)	(42.6)
Other comprehensive income (loss) before reclassifications		18.0	13.8		40.6	(3.0)
Reclassifications for amortization of unrecognized net loss	[1]	0.0	0.0		0.0	0.0
Reclassifications for realized (gains) losses - net	[2]	0.0	0.0		0.0	0.0
Foreign currency translation gains			0.0			(0.6)	[3]
Income taxes		0.0	0.0		0.0	0.0
Total other comprehensive income (loss)		18.0	13.8		40.6	(3.6)
Ending balance		(20.8)	(46.2)	(60.0)	(20.8)	(46.2)
Defined Benefit Plans [Member]
Other comprehensive loss [Abstract]
Beginning balance		(158.4)	(134.1)		(160.9)	(136.3)
Other comprehensive income (loss) before reclassifications		0.0	0.0		0.0	0.0
Reclassifications for amortization of unrecognized net loss	[1]	1.6	1.4		4.9	4.2
Reclassifications for realized (gains) losses - net	[2]	0.0	0.0		0.0	0.0
Foreign currency translation gains			0.0			0.0
Income taxes		(0.3)	(0.4)		(1.1)	(1.0)
Total other comprehensive income (loss)		1.3	1.0		3.8	3.2
Ending balance		(157.1)	(133.1)	(134.1)	(157.1)	(133.1)
Cash Flow Hedges [Member]
Other comprehensive loss [Abstract]
Beginning balance		0.4	(0.5)		(1.0)	0.5
Other comprehensive income (loss) before reclassifications		0.4	0.3		1.5	(1.3)
Reclassifications for amortization of unrecognized net loss	[1]	0.0	0.0		0.0	0.0
Reclassifications for realized (gains) losses - net	[2]	(0.4)	0.5		0.4	0.7
Foreign currency translation gains			0.0			0.0
Income taxes		0.0	(0.2)		(0.5)	0.2
Total other comprehensive income (loss)		0.0	0.6		1.4	(0.4)
Ending balance		$ 0.4	$ 0.1	$ (0.5)	$ 0.4	$ 0.1

[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. Refer to Note 5 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.