General (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Mar. 31, 2019	Mar. 31, 2018
Leases [Abstract]
Right-of-use assets	$ 64.7		$ 64.7	$ 61.3
Operating lease liabilities, Other current liabilities	10.1		10.1
Operating lease liabilities, Other noncurrent liabilities	53.1		53.1
Operating leases, right-of-use liabilities	63.2		63.2
New Accounting Guidance Adopted [Abstract]
Retained earnings	475.4		475.4	472.1
Real Estate Leases [Member]
Leases [Abstract]
Right-of-use assets				61.3
Operating lease liabilities, Other current liabilities				12.4
Operating lease liabilities, Other noncurrent liabilities				48.9
Build to Suit Arrangements [Member]
Leases [Abstract]
Right-of-use assets				$ 5.2
Operating leases, right-of-use liabilities	$ 5.2		$ 5.2
AIAC Air Conditioning South Africa (Pty) Ltd [Member]
Sale of Business [Abstract]
Selling price		$ 0.5
Gain (loss) on sale of business		(1.7)
Gain (loss) on write-off of accumulated foreign currency translation		(0.8)
AIAC Air Conditioning South Africa (Pty) Ltd [Member] | Maximum [Member]
Sale of Business [Abstract]
Annual net sales attributable to disposed business		$ 2.0
Nikkei Heat Exchanger Company, Ltd [Member]
Sale of Business [Abstract]
Ownership percentage	50.00%		50.00%
Selling price	$ 3.8		$ 3.8
Gain (loss) on sale of business	0.1		$ 0.1
Gain (loss) on write-off of accumulated foreign currency translation	$ 0.6
ASU 2014-09 [Member]
New Accounting Guidance Adopted [Abstract]
Retained earnings					$ 0.7
ASU 2016-16 [Member]
New Accounting Guidance Adopted [Abstract]
Retained earnings					$ (8.3)