Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019
Segment Reporting Information [Abstract]
Net sales	$ 500.2	$ 548.9	$ 1,029.2	$ 1,115.0
Gross profit	$ 75.7	$ 87.9	$ 159.1	$ 182.2
Gross profit (% of sales)	15.10%	16.00%	15.50%	16.30%
Operating income	$ 6.0	$ 22.8	$ 24.1	$ 57.6
Total assets	1,564.5		1,564.5		$ 1,538.0	[1]
Operating lease assets	64.7		64.7		61.3
VTS [Member]
Segment Reporting Information [Abstract]
Net sales	299.3	335.6	625.8	688.4
CIS [Member]
Segment Reporting Information [Abstract]
Net sales	156.7	178.2	325.5	362.1
BHVAC [Member]
Segment Reporting Information [Abstract]
Net sales	56.0	50.7	105.0	95.7
Total Segments [Member]
Segment Reporting Information [Abstract]
Net sales	512.0	564.5	1,056.3	1,146.2
Operating Segments [Member]
Segment Reporting Information [Abstract]
Net sales	500.2	548.9	1,029.2	1,115.0
Gross profit	$ 75.9	$ 87.9	$ 158.9	$ 182.1
Gross profit (% of sales)	14.80%	15.60%	15.00%	15.90%
Operating income	$ 24.7	$ 31.8	$ 56.3	$ 73.7
Operating Segments [Member] | VTS [Member]
Segment Reporting Information [Abstract]
Net sales	288.8	321.5	601.4	659.8
Gross profit	$ 35.3	$ 44.6	$ 80.3	$ 98.6
Gross profit (% of sales)	11.80%	13.30%	12.80%	14.30%
Operating income	$ 7.4	$ 14.1	$ 24.7	$ 39.6
Total assets	755.3		755.3		749.9	[1]
Operating Segments [Member] | CIS [Member]
Segment Reporting Information [Abstract]
Net sales	155.7	177.4	323.6	360.9
Gross profit	$ 22.9	$ 28.3	$ 47.2	$ 56.9
Gross profit (% of sales)	14.60%	15.90%	14.50%	15.70%
Operating income	$ 8.5	$ 12.9	$ 17.5	$ 26.1
Total assets	612.8		612.8		604.2	[1]
Operating Segments [Member] | BHVAC [Member]
Segment Reporting Information [Abstract]
Net sales	55.7	50.0	104.2	94.3
Gross profit	$ 17.7	$ 15.0	$ 31.4	$ 26.6
Gross profit (% of sales)	31.70%	29.50%	29.90%	27.80%
Operating income	$ 8.8	$ 4.8	$ 14.1	$ 8.0
Total assets	103.4		103.4		89.4	[1]
Corporate and Eliminations [Member]
Segment Reporting Information [Abstract]
Net sales	(11.8)	(15.6)	(27.1)	(31.2)
Gross profit	$ (0.2)	$ 0.0	$ 0.2	$ 0.1
Gross profit (% of sales)	0.00%	0.00%	0.00%	0.00%
Operating income	$ (18.7)	$ (9.0)	$ (32.2)	$ (16.1)
Total assets	93.0		93.0		$ 94.5	[1]
Inter-segment Sales [Member]
Segment Reporting Information [Abstract]
Net sales	11.8	15.6	27.1	31.2
Inter-segment Sales [Member] | VTS [Member]
Segment Reporting Information [Abstract]
Net sales	10.5	14.1	24.4	28.6
Inter-segment Sales [Member] | CIS [Member]
Segment Reporting Information [Abstract]
Net sales	1.0	0.8	1.9	1.2
Inter-segment Sales [Member] | BHVAC [Member]
Segment Reporting Information [Abstract]
Net sales	$ 0.3	$ 0.7	$ 0.8	$ 1.4

[1] The Company adopted new lease accounting guidance and, as a result, recorded $61.3 million of operating lease assets on its consolidated balance sheet on April 1, 2019.  See Note 1 for additional information.