Segment Information - Financial Information By Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Identifiable assets	$ 6,747.2		$ 6,446.5
Capital expenditures	16.8	$ 19.3
Depreciation	14.8	14.9
Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	6,347.3		6,005.5
Capital expenditures	13.0	16.4
Depreciation	12.3	12.7
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Segment Reporting Information [Line Items]
Identifiable assets	399.9		441.0
Capital expenditures	3.8	2.9
Depreciation	2.5	2.2
Flow | Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	1,668.1		1,590.7
Capital expenditures	3.8	3.0
Depreciation	5.2	5.3
Water Solutions | Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	2,648.5		2,613.5
Capital expenditures	2.8	10.1
Depreciation	4.0	4.4
Pool | Operating Segments
Segment Reporting Information [Line Items]
Identifiable assets	2,030.7		$ 1,801.3
Capital expenditures	6.4	3.3
Depreciation	$ 3.1	$ 3.0