Basis of Presentation and Summary of Significant Accounting Policies - Net Sales Information (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 796.0	$ 798.5	$ 713.3	$ 710.0	$ 755.2	$ 713.6	$ 799.5	$ 688.9	$ 3,017.8	[1]	$ 2,957.2	[1]	$ 2,965.1	[1]
Residential
Disaggregation of Revenue [Line Items]
Net sales									1,883.4		1,668.2		1,665.9
Commercial
Disaggregation of Revenue [Line Items]
Net sales									528.6		627.3		630.7
Industrial
Disaggregation of Revenue [Line Items]
Net sales									605.8		661.7		668.5
U.S.
Disaggregation of Revenue [Line Items]
Net sales									2,011.7		1,866.7		1,858.1
Western Europe
Disaggregation of Revenue [Line Items]
Net sales									375.3		401.6		402.7
Developing
Disaggregation of Revenue [Line Items]
Net sales									427.5		480.6		476.5
Other Developed
Disaggregation of Revenue [Line Items]
Net sales									$ 203.3		$ 208.3		$ 227.8

[1] (1) One customer in the Consumer Solutions segment, Pool Corporation, represented approximately 15% of our consolidated net sales in 2020, 2019 and 2018.