Segment Information - Financial Information By Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Segment Reporting [Line Items]
Identifiable assets	$ 7,072.0		$ 6,868.8
Capital expenditures	18.5	$ 16.8
Depreciation	14.6	14.8
Operating Segments
Segment Reporting [Line Items]
Identifiable assets	6,723.2		6,425.4
Capital expenditures	15.0	13.0
Depreciation	12.7	12.3
Corporate and other
Segment Reporting [Line Items]
Identifiable assets	348.8		443.4
Capital expenditures	3.5	3.8
Depreciation	1.9	2.5
Flow | Operating Segments
Segment Reporting [Line Items]
Identifiable assets	1,315.0		1,640.2
Capital expenditures	2.8	2.9
Depreciation	3.6	3.7
Water Solutions | Operating Segments
Segment Reporting [Line Items]
Identifiable assets	3,292.8		2,900.9
Capital expenditures	4.8	3.7
Depreciation	5.4	5.5
Pool | Operating Segments
Segment Reporting [Line Items]
Identifiable assets	2,115.4		$ 1,884.3
Capital expenditures	7.4	6.4
Depreciation	$ 3.7	$ 3.1