Segment Information - Financial Information By Reportable Segment (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net sales	[1]	$ 4,104.5	$ 4,121.8	$ 3,764.8
Segment Income (Loss)	[1]	855.1	767.7	685.9
Identifiable assets	[2]	6,563.3	6,447.5	4,753.6
Capital expenditures		76.0	85.2	60.2
Depreciation		$ 59.5	$ 54.1	$ 51.2
One customer | Net sales | Customer concentration risk
Segment Reporting Information [Line Items]
Concentration risk percentage		15.00%	20.00%	20.00%
Flow
Segment Reporting Information [Line Items]
Net sales		$ 1,582.1	$ 1,500.8	$ 1,421.4
Segment Income (Loss)		282.3	242.3	213.3
Identifiable assets	[2]	1,709.7	1,722.4	1,716.4
Capital expenditures		19.6	24.0	23.0
Depreciation		21.1	19.5	21.4
Water Solutions
Segment Reporting Information [Line Items]
Net sales		1,177.2	986.8	769.9
Segment Income (Loss)		247.6	149.0	101.7
Identifiable assets		2,695.2	2,786.4	1,181.6
Capital expenditures		23.0	24.7	16.4
Depreciation		18.1	18.4	15.8
Pool
Segment Reporting Information [Line Items]
Net sales		1,343.6	1,632.7	1,572.0
Segment Income (Loss)		417.0	462.1	452.7
Identifiable assets	[2]	1,679.8	1,710.3	1,641.4
Capital expenditures		17.3	28.8	16.1
Depreciation		11.4	8.9	7.9
Corporate Segment
Segment Reporting Information [Line Items]
Net sales		1.6	1.5	1.5
Segment Income (Loss)		(91.8)	(85.7)	(81.8)
Identifiable assets	[2]	478.6	228.4	214.2
Capital expenditures		16.1	7.7	4.7
Depreciation		$ 8.9	$ 7.3	$ 6.1

[1] (1) One customer in the Pool business represented approximately 15% of our consolidated net sales in 2023 and 20% of our consolidated net sales in both 2022 and 2021.

[2] All cash and cash equivalents are included in “Other.”