Contingencies and Environmental Remediation (Details) $ in Millions				2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 16, 2016 USD ($)	Sep. 28, 2014 USD ($)	Dec. 12, 2013 USD ($)	Dec. 31, 2014 item	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Litigation contingencies
Reasonably possible loss in excess of the amount accrued for its legal contingencies					$ 3.7	$ 3.7
Connector Class Action
Litigation contingencies
Number of class action complaints | item				3
Total settlement amount on proposed litigation	$ 14.0
Possible loss on proposed estimate	4.1
Estimated insurance receivable	$ 9.9
Liability recorded					14.0	14.0
Liability recorded, current					7.8	7.8
Liability recorded, noncurrent					6.2	6.2
Insurance proceeds, current assets					9.5	9.5
Pre-tax litigation settlement amount, charged to earnings					3.5
Trabakoolas et al., v, Watts Water Technologies, Inc., et al.
Litigation contingencies
Total settlement amount			$ 23.0
Possible loss			14.0
Insurance proceeds			$ 9.0
Liability recorded					$ 6.5	6.5		$ 22.6
Liability recorded, current								12.7
Liability recorded, noncurrent								9.9
Insurance proceeds, current assets								$ 9.0
Receivable receipts for insurance proceeds		$ 9.0
Reduction in liability						$ 2.3	$ 13.8
Period for payment of remaining liability						3 years
Asbestos Litigation
Litigation contingencies
Number of lawsuits the entity is defending in different jurisdictions | item						310