Goodwill and Other Identifiable Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($)
Goodwill [Roll Forward]
Beginning Balance	$ 3,538.1
Foreign currency translation/other	(13.4)
Ending Balance	3,524.7
Previously Reported
Goodwill [Roll Forward]
Beginning Balance	3,538.1
Reallocation
Goodwill [Roll Forward]
Beginning Balance	0.0
Flow
Goodwill [Roll Forward]
Beginning Balance	641.2
Foreign currency translation/other	(7.4)
Ending Balance	633.8
Flow | Previously Reported
Goodwill [Roll Forward]
Beginning Balance	967.5
Flow | Reallocation
Goodwill [Roll Forward]
Beginning Balance	(326.3)
Flow | Reallocation | Fair Value Impact
Goodwill [Roll Forward]
Beginning Balance	(44.2)
Flow | Reallocation | Segment Composition
Goodwill [Roll Forward]
Beginning Balance	(282.1)
Water Solutions
Goodwill [Roll Forward]
Beginning Balance	1,733.4
Foreign currency translation/other	(6.0)
Ending Balance	1,727.4
Water Solutions | Previously Reported
Goodwill [Roll Forward]
Beginning Balance	1,407.1
Water Solutions | Reallocation
Goodwill [Roll Forward]
Beginning Balance	326.3
Water Solutions | Reallocation | Fair Value Impact
Goodwill [Roll Forward]
Beginning Balance	44.2
Water Solutions | Reallocation | Segment Composition
Goodwill [Roll Forward]
Beginning Balance	282.1
Pool
Goodwill [Roll Forward]
Beginning Balance	1,163.5
Foreign currency translation/other	0.0
Ending Balance	1,163.5
Pool | Previously Reported
Goodwill [Roll Forward]
Beginning Balance	1,163.5
Pool | Reallocation
Goodwill [Roll Forward]
Beginning Balance	$ 0.0