Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018
Segment Reporting Information [Abstract]
Net sales	$ 566.1	$ 515.5
Gross profit	$ 94.3	$ 88.5
Gross profit (% of sales)	16.70%	17.20%
Operating income (loss)	$ 34.8	$ 27.6
Total assets	1,562.7		$ 1,573.4
Vehicular Thermal Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	352.8	315.3
Commercial and Industrial Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	183.9	171.4
Building HVAC Systems [Member]
Segment Reporting Information [Abstract]
Net sales	45.0	43.0
Total Segments [Member]
Segment Reporting Information [Abstract]
Net sales	581.7	529.7
Operating Segments [Member]
Segment Reporting Information [Abstract]
Net sales	566.1	515.5
Gross profit	$ 94.2	$ 88.6
Gross profit (% of sales)	16.20%	16.70%
Operating income (loss)	$ 41.9	$ 36.7
Operating Segments [Member] \| Vehicular Thermal Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	338.3	301.4
Gross profit	$ 54.0	$ 50.8
Gross profit (% of sales)	15.30%	16.10%
Operating income (loss)	$ 25.5	$ 22.2
Total assets	746.3		754.8
Operating Segments [Member] \| Commercial and Industrial Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	183.5	171.1
Gross profit	$ 28.6	$ 26.7
Gross profit (% of sales)	15.60%	15.60%
Operating income (loss)	$ 13.2	$ 11.4
Total assets	634.1		630.2
Operating Segments [Member] \| Building HVAC Systems [Member]
Segment Reporting Information [Abstract]
Net sales	44.3	43.0
Gross profit	$ 11.6	$ 11.1
Gross profit (% of sales)	25.90%	25.90%
Operating income (loss)	$ 3.2	$ 3.1
Total assets	92.2		88.1
Corporate and Eliminations [Member]
Segment Reporting Information [Abstract]
Net sales	(15.6)	(14.2)
Gross profit	$ 0.1	$ (0.1)
Gross profit (% of sales)	0.00%	0.00%
Operating income (loss)	$ (7.1)	$ (9.1)
Total assets	90.1		$ 100.3
Inter-segment Sales [Member]
Segment Reporting Information [Abstract]
Net sales	15.6	14.2
Inter-segment Sales [Member] \| Vehicular Thermal Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	14.5	13.9
Inter-segment Sales [Member] \| Commercial and Industrial Solutions [Member]
Segment Reporting Information [Abstract]
Net sales	0.4	0.3
Inter-segment Sales [Member] \| Building HVAC Systems [Member]
Segment Reporting Information [Abstract]
Net sales	$ 0.7	$ 0.0

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