Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Segment Reporting Information [Abstract]
Net sales	$ 541.0	$ 512.7	$ 1,656.0	$ 1,536.5
Gross profit	$ 91.7	$ 85.4	$ 273.9	$ 260.0
Gross profit (% of sales)	16.90%	16.70%	16.50%	16.90%
Operating income	$ 33.6	$ 13.9	$ 91.2	$ 65.0
Total assets	1,512.7		1,512.7		$ 1,573.4
Vehicular Thermal Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	323.3	313.0	1,011.7	938.9
Commercial and Industrial Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	167.0	159.0	529.1	494.2
Building HVAC Systems [Member]
Segment Reporting Information [Abstract]
Net sales	64.2	56.1	159.9	147.9
Total Segments [Member]
Segment Reporting Information [Abstract]
Net sales	554.5	528.1	1,700.7	1,581.0
Operating Segments [Member]
Segment Reporting Information [Abstract]
Net sales	541.0	512.7	1,656.0	1,536.5
Gross profit	$ 91.6	$ 85.5	$ 273.7	$ 260.1
Gross profit (% of sales)	16.50%	16.20%	16.10%	16.50%
Operating income	$ 41.6	$ 24.0	$ 115.3	$ 94.9
Operating Segments [Member] | Vehicular Thermal Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	311.5	298.6	971.3	896.4
Gross profit	$ 41.4	$ 46.5	$ 140.0	$ 144.4
Gross profit (% of sales)	12.80%	14.90%	13.80%	15.40%
Operating income	$ 15.5	$ 18.7	$ 55.1	$ 59.8
Total assets	711.4		711.4		754.8
Operating Segments [Member] | Commercial and Industrial Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	166.1	158.7	527.0	493.4
Gross profit	$ 28.2	$ 20.0	$ 85.1	$ 70.7
Gross profit (% of sales)	16.90%	12.60%	16.10%	14.30%
Operating income	$ 13.1	$ (3.9)	$ 39.2	$ 16.5
Total assets	617.2		617.2		630.2
Operating Segments [Member] | Building HVAC Systems [Member]
Segment Reporting Information [Abstract]
Net sales	63.4	55.4	157.7	146.7
Gross profit	$ 22.0	$ 19.0	$ 48.6	$ 45.0
Gross profit (% of sales)	34.30%	33.80%	30.40%	30.40%
Operating income	$ 13.0	$ 9.2	$ 21.0	$ 18.6
Total assets	89.2		89.2		88.1
Corporate and Eliminations [Member]
Segment Reporting Information [Abstract]
Net sales	(13.5)	(15.4)	(44.7)	(44.5)
Gross profit	$ 0.1	$ (0.1)	$ 0.2	$ (0.1)
Gross profit (% of sales)	0.00%	0.00%	0.00%	0.00%
Operating income	$ (8.0)	$ (10.1)	$ (24.1)	$ (29.9)
Total assets	94.9		94.9		$ 100.3
Inter-segment Sales [Member]
Segment Reporting Information [Abstract]
Net sales	13.5	15.4	44.7	44.5
Inter-segment Sales [Member] | Vehicular Thermal Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	11.8	14.4	40.4	42.5
Inter-segment Sales [Member] | Commercial and Industrial Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	0.9	0.3	2.1	0.8
Inter-segment Sales [Member] | Building HVAC Systems [Member]
Segment Reporting Information [Abstract]
Net sales	$ 0.8	$ 0.7	$ 2.2	$ 1.2