Revenue Recognition - Segment Sales Disaggregated by Major Product Line (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Net sales	$ 963.9	$ 978.8
North America
Disaggregation of Revenue [Line Items]
Net sales	743.4	761.6
Rest of World
Disaggregation of Revenue [Line Items]
Net sales	220.5	217.2
Operating Segments
Disaggregation of Revenue [Line Items]
Net sales	975.4	993.2
Operating Segments \| North America
Disaggregation of Revenue [Line Items]
Net sales	748.7	766.3
Operating Segments \| Rest of World
Disaggregation of Revenue [Line Items]
Net sales	226.7	226.9
Operating Segments \| Rest of World \| China
Disaggregation of Revenue [Line Items]
Net sales	187.2	200.6
Operating Segments \| Rest of World \| All other Rest of World
Disaggregation of Revenue [Line Items]
Net sales	39.5	26.3
Operating Segments \| Water heaters and related parts \| North America
Disaggregation of Revenue [Line Items]
Net sales	624.6	648.3
Operating Segments \| Boilers and related parts \| North America
Disaggregation of Revenue [Line Items]
Net sales	64.4	58.7
Operating Segments \| Water treatment products and related parts \| North America
Disaggregation of Revenue [Line Items]
Net sales	59.7	59.3
Inter-segment Elimination
Disaggregation of Revenue [Line Items]
Net sales	(11.5)	(14.4)
Inter-segment Elimination \| North America
Disaggregation of Revenue [Line Items]
Net sales	(5.3)	(4.7)
Inter-segment Elimination \| Rest of World
Disaggregation of Revenue [Line Items]
Net sales	$ (6.2)	$ (9.7)