Goodwill and Other Identifiable Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Goodwill [Roll Forward]
Beginning Balance	$ 3,286.6	$ 3,274.6
Acquisitions	169.2	56.6
Foreign  currency translation	82.3	(44.6)
Ending Balance	3,538.1	3,286.6
Flow
Goodwill [Roll Forward]
Beginning Balance	730.4	767.1
Acquisitions	169.2	0.0
Foreign  currency translation	67.9	(36.7)
Ending Balance	967.5	730.4
Water Solutions
Goodwill [Roll Forward]
Beginning Balance	1,392.7	1,400.6
Acquisitions	0.0	0.0
Foreign  currency translation	14.4	(7.9)
Ending Balance	1,407.1	1,392.7
Pool
Goodwill [Roll Forward]
Beginning Balance	1,163.5	1,106.9
Acquisitions	0.0	56.6
Foreign  currency translation	0.0	0.0
Ending Balance	$ 1,163.5	$ 1,163.5