CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 28, 2014	Sep. 28, 2014
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net loss, tax benefits	$ 6.6	$ 6.6

Represents the income tax effect attributable to pension and other postretirement benefit plans, after tax.

No definition available.

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