Segment Information - Financial Information By Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Identifiable assets	$ 6,479.5		$ 6,479.5		$ 6,446.5
Capital expenditures	10.9	$ 17.0	27.7	$ 36.3
Depreciation	14.6	15.5	29.4	30.4
Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	6,035.4		6,035.4		6,005.5
Capital expenditures	9.8	13.9	22.8	30.3
Depreciation	12.8	13.2	25.1	25.9
Corporate and other
Segment Reporting Information [Line Items]
Identifiable assets	444.1		444.1		441.0
Capital expenditures	1.1	3.1	4.9	6.0
Depreciation	1.8	2.3	4.3	4.5
Flow | Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	1,703.0		1,703.0		1,590.7
Capital expenditures	3.1	4.2	6.9	7.2
Depreciation	5.2	5.5	10.4	10.8
Water Solutions | Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	2,589.5		2,589.5		2,613.5
Capital expenditures	2.9	4.8	5.7	14.9
Depreciation	4.0	4.4	8.0	8.8
Pool | Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	1,742.9		1,742.9		$ 1,801.3
Capital expenditures	3.8	4.9	10.2	8.2
Depreciation	$ 3.6	$ 3.3	$ 6.7	$ 6.3