Goodwill and Intangibles - Goodwill (Details) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 27, 2020 USD ($)	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Oct. 25, 2020 USD ($)
Gross Balance
Balance at the beginning of the period			$ 748.2	$ 711.9
Acquired During the Period			9.4	38.3
Foreign Currency Translation and Other			11.9	(2.0)
Balance at the end of the period	$ 769.5		769.5	748.2
Accumulated Impairment Losses
Balance at the beginning of the period			(167.1)	(167.1)
Balance at the end of the period	(167.1)		(167.1)	(167.1)
Goodwill impairment charges			0.0	0.0
Net Goodwill	602.4		$ 602.4	581.1	$ 590.8
Number of reporting units | item			7
Number of reporting units with goodwill | item			6
Number of reporting units with no goodwill | item			1
Acquisitions during the year | item			2
Goodwill impairment charges			$ 0.0	0.0
Heating and Hot Water Solutions
Gross Balance
Balance at the end of the period	218.9		218.9
Americas
Gross Balance
Balance at the beginning of the period			476.8	438.1
Acquired During the Period	5.5		5.5	38.3
Foreign Currency Translation and Other			0.2	0.4
Balance at the end of the period	482.5		482.5	476.8
Accumulated Impairment Losses
Balance at the beginning of the period			(24.5)	(24.5)
Balance at the end of the period	(24.5)		(24.5)	(24.5)
Net Goodwill	458.0		458.0	452.3
Europe
Gross Balance
Balance at the beginning of the period			241.4	243.7
Foreign Currency Translation and Other			10.7	(2.3)
Balance at the end of the period	252.1		252.1	241.4
Accumulated Impairment Losses
Balance at the beginning of the period			(129.7)	(129.7)
Balance at the end of the period	(129.7)		(129.7)	(129.7)
Net Goodwill	122.4		122.4	111.7
APMEA
Gross Balance
Balance at the beginning of the period			30.0	30.1
Acquired During the Period		$ 3.9	3.9
Foreign Currency Translation and Other			1.0	(0.1)
Balance at the end of the period	34.9		34.9	30.0
Accumulated Impairment Losses
Balance at the beginning of the period			(12.9)	(12.9)
Balance at the end of the period	(12.9)		(12.9)	(12.9)
Net Goodwill	22.0		22.0	$ 17.1
Water Quality Products
Gross Balance
Balance at the end of the period	$ 0.0		$ 0.0