Debt (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 29, 2013
Credit Agreement
Credit Agreement
Multi-currency borrowing capacity	$ 300.0
Term of senior unsecured revolving credit facility	5 years
Potential additional borrowing capacity	150.0
Sublimit on letters of credit	75.0
Unused and available credit under the credit agreement	270.4
Stand-by letters of credit outstanding	29.6
Eurocurrency rate loans \| LIBOR \| Minimum
Credit Agreement
Interest rate added to base rate (as a percent)	1.70%
Eurocurrency rate loans \| LIBOR \| Maximum
Credit Agreement
Interest rate added to base rate (as a percent)	2.30%
Base rate loans and swing line loans \| Minimum
Credit Agreement
Interest rate added to base rate (as a percent)	0.70%
Base rate loans and swing line loans \| Maximum
Credit Agreement
Interest rate added to base rate (as a percent)	1.30%
Base rate loans and swing line loans \| LIBOR
Credit Agreement
Interest rate added to base rate (as a percent)	1.00%
Base rate loans and swing line loans \| Federal funds
Credit Agreement
Interest rate added to base rate (as a percent)	0.50%
Unsecured senior notes
Credit Agreement
Repayment of debt	$ 75.0

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Decrease for amounts repaid on the debt instrument for the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-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 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage points added to the specified reference rate to compute the variable rate on the debt instrument, in addition to the percentage points added regardless of specified reference rate.

+ References

No definition available.

+ Details

Name:	wts_DebtInstrumentBasisSpreadOnVariableRateAdditional
Namespace Prefix:	wts_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the maximum amount of the guarantees available through letters of credit.

+ References

No definition available.

+ Details

Name:	wts_LettersOfCreditMaximumAmount
Namespace Prefix:	wts_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the additional amount of borrowing capacity that may be added under the credit facility.

+ References

No definition available.

+ Details

Name:	wts_LineOfCreditFacilityOptionForAdditionalBorrowingCapacity
Namespace Prefix:	wts_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the term of the unsecured revolving credit facility.

+ References

No definition available.

+ Details

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