The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 51
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_BusinessAcquisitionCostOfAcquiredEntityPurchasePrice
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of goodwill arising from a business combination, which is the excess of the cost of the acquired entity over the amounts assigned to assets acquired and liabilities assumed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 52
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 53
-Subparagraph d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_BusinessAcquisitionPurchasePriceAllocationGoodwillAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The calculated weighted-average useful life of all finite-lived intangible assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16265-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Namespace Prefix:	us-gaap
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The cost of the acquired entity before working capital and related adjustments.

+ Details

Name:	wts_BusinessAcquisitionCostOfAcquiredEntityPurchasePriceGross
Namespace Prefix:	wts
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cost of the acquired entity attributable to working capital and related adjustments.

+ Details

Name:	wts_BusinessAcquisitionCostOfAcquiredEntityWorkingCapitalAndOtherAdjustments
Namespace Prefix:	wts
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of acquisition cost of a business combination allocated to intangible assets.

+ Details

Name:	wts_BusinessAcquisitionPurchasePriceAllocationIntangibleAssets
Namespace Prefix:	wts
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Accounting Policies (Details 2) In Millions, unless otherwise specified	6 Months Ended			1 Months Ended	6 Months Ended	1 Months Ended
	Jul. 03, 2011	Apr. 30, 2011 Danfoss Socla S.A.S USD ($)	Apr. 30, 2011 Danfoss Socla S.A.S EUR (€)	Apr. 30, 2011 Customer relationships	Jul. 03, 2011 Customer relationships	Apr. 30, 2011 Trade name
Acquisition
Aggregate consideration, gross			€ 120.0
Estimated working capital and related adjustments			3.4
Aggregate consideration, net		172.8	116.6
Purchase price allocated to goodwill		69.3
Purchase price allocated to intangible assets		$ 46.3
Estimated lives of intangible assets (in years)	13.4			10	7.8	20