Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

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Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of projected intercompany purchase transactions hedged for the next twelve months by forward exchange contracts.

+ References

No definition available.

+ Details

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Namespace Prefix:	wts_
Data Type:	num:percentItemType
Balance Type:	na
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- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
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Period Type:

Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative instruments
Percentage of projected intercompany purchases hedged by forward exchange contracts	50.00%
Period of projected intercompany purchase transactions	12 months
Amount of Gain or (Loss) Recognized in Income on Derivatives
Income from derivatives recorded to other expense (income), net in statement of operations	$ 0	$ 0.1	$ 0.1
Forward exchange contracts \| Purchased contracts \| Minimum
Derivative instruments
Notional amount	0
Forward exchange contracts \| Purchased contracts \| Maximum
Derivative instruments
Notional amount	10.0
Forward exchange contracts \| Non designated
Derivative instruments
Notional amount	$ 1.0