Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Segment Reporting Information [Abstract]
Net sales	$ 461.4	$ 500.2	$ 809.2	$ 1,029.2
Gross profit	$ 80.8	$ 75.7	$ 126.9	$ 159.1
Gross profit (% of sales)	17.50%	15.10%	15.70%	15.50%
Operating income	$ 28.5	$ 6.0	$ 25.3	$ 24.1
Total assets	1,510.9		1,510.9		$ 1,536.1
CIS [Member]
Segment Reporting Information [Abstract]
Net sales	134.1	156.7	256.6	325.5
BHVAC [Member]
Segment Reporting Information [Abstract]
Net sales	61.9	56.0	109.5	105.0
HDE [Member]
Segment Reporting Information [Abstract]
Net sales	165.6	187.2	289.1	403.6
Automotive [Member]
Segment Reporting Information [Abstract]
Net sales	109.9	115.7	172.0	229.3
Total Segments [Member]
Segment Reporting Information [Abstract]
Net sales	471.5	515.6	827.2	1,063.4
Operating Segments [Member]
Segment Reporting Information [Abstract]
Net sales	461.4	500.2	809.2	1,029.2
Gross profit	$ 81.2	$ 76.0	$ 127.3	$ 159.0
Gross profit (% of sales)	17.20%	14.70%	15.40%	15.00%
Operating income	$ 40.0	$ 24.8	$ 40.8	$ 56.4
Operating Segments [Member] | CIS [Member]
Segment Reporting Information [Abstract]
Net sales	133.2	155.7	254.5	323.6
Gross profit	$ 19.3	$ 22.9	$ 34.8	$ 47.2
Gross profit (% of sales)	14.40%	14.60%	13.50%	14.50%
Operating income	$ 5.6	$ 8.5	$ 5.6	$ 17.5
Total assets	598.2		598.2		617.7
Operating Segments [Member] | BHVAC [Member]
Segment Reporting Information [Abstract]
Net sales	61.9	55.7	109.3	104.2
Gross profit	$ 21.7	$ 17.7	$ 36.2	$ 31.4
Gross profit (% of sales)	35.10%	31.70%	33.10%	29.90%
Operating income	$ 13.1	$ 8.8	$ 20.2	$ 14.1
Total assets	105.4		105.4		102.3
Operating Segments [Member] | HDE [Member]
Segment Reporting Information [Abstract]
Net sales	157.6	173.9	275.9	373.6
Gross profit	$ 23.6	$ 22.4	$ 34.9	$ 54.9
Gross profit (% of sales)	14.20%	12.00%	12.10%	13.60%
Operating income	$ 13.3	$ 7.1	$ 10.8	$ 24.4
Total assets	418.8		418.8		417.4
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Abstract]
Net sales	108.7	114.9	169.5	227.8
Gross profit	$ 16.6	$ 13.0	$ 21.4	$ 25.5
Gross profit (% of sales)	15.20%	11.20%	12.50%	11.10%
Operating income	$ 8.0	$ 0.4	$ 4.2	$ 0.4
Total assets	281.7		281.7		272.5
Corporate and Eliminations [Member]
Segment Reporting Information [Abstract]
Net sales	(10.1)	(15.4)	(18.0)	(34.2)
Gross profit	$ (0.4)	$ (0.3)	$ (0.4)	$ 0.1
Gross profit (% of sales)	0.00%	0.00%	0.00%	0.00%
Operating income	$ (11.5)	$ (18.8)	$ (15.5)	$ (32.3)
Total assets	106.8		106.8		$ 126.2
Inter-segment Sales [Member]
Segment Reporting Information [Abstract]
Net sales	10.1	15.4	18.0	34.2
Inter-segment Sales [Member] | CIS [Member]
Segment Reporting Information [Abstract]
Net sales	0.9	1.0	2.1	1.9
Inter-segment Sales [Member] | BHVAC [Member]
Segment Reporting Information [Abstract]
Net sales	0.0	0.3	0.2	0.8
Inter-segment Sales [Member] | HDE [Member]
Segment Reporting Information [Abstract]
Net sales	8.0	13.3	13.2	30.0
Inter-segment Sales [Member] | Automotive [Member]
Segment Reporting Information [Abstract]
Net sales	$ 1.2	$ 0.8	$ 2.5	$ 1.5