Consolidated Statements of Comprehensive (Loss) Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consolidated Statements of Comprehensive (Loss) Income
Other Comprehensive Income Defined Benefit Plan Income Tax Effect	$ 6.9	$ 0.8	$ 4.1
Other Comprehensive Income Amortization of Net Losses included in Net Periodic Pension Cost Tax Effect	$ 0.5	$ 0.4	$ 0.2

Represents the amount of tax effect on the amortization of net losses included in net periodic pension cost.

No definition available.

Name:	wts_OtherComprehensiveIncomeAmortizationOfNetLossesIncludedInNetPeriodicPensionCostTaxEffect
Namespace Prefix:	wts_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration