Name:	us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph h

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Maximum percentage of employee gross pay, by the terms of the plan, that the employer may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the first level of employee contributions (percentage of compensation) which are matched by the employer.

+ References

No definition available.

+ Details

Name:	wts_DefinedContributionPlanEmployerMatchEmployeeContributionLevelOne
Namespace Prefix:	wts_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the employer maximum matching contribution of the first level of an employee's contributions.

+ References

No definition available.

+ Details

Name:	wts_DefinedContributionPlanEmployerMatchLevelOneMaximum
Namespace Prefix:	wts_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	wts_SupplementalCompensationAgreementAbstract
Namespace Prefix:	wts_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The compensation expense paid during the period pertaining to the supplemental compensation agreement.

+ References

No definition available.

+ Details

Name:	wts_SupplementalCompensationAgreementAnnualCompensationPaid
Namespace Prefix:	wts_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the service period per year required to be worked under supplemental compensation agreement in return for certain annual compensation.

+ References

No definition available.

+ Details

Name:	wts_SupplementalCompensationAgreementServicePeriodPerYear
Namespace Prefix:	wts_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Employee Benefit Plans (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Employee Benefit Plans
Base contribution as a percentage of employee gross pay (as a percent)	2.00%
Employer maximum match of an employee's contributions of first 4% of eligible compensation (as a percent)	100.00%
Percentage of eligible compensation, matched 100% by employer	4.00%
Company's matching contributions under certain 401(k) savings plans	$ 4.0	$ 0.5	$ 0.5	$ 0.5
Employee Benefit Plans
Charges for pension plans		8.3	6.9
Supplemental compensation agreement with Timothy P. Horne
Supplemental compensation paid on an annual basis	0.6	0.5	0.5
Minimum
Supplemental compensation agreement with Timothy P. Horne
Hours per year required to be worked as a consultant in return for certain annual compensation	300 hours
Maximum
Supplemental compensation agreement with Timothy P. Horne
Hours per year required to be worked as a consultant in return for certain annual compensation	500 hours
European pension plans
Employee Benefit Plans
Charges for pension plans	$ 6.0	$ 6.2	$ 3.5