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

No definition available.

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
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

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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.

+ References

No definition available.

+ 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

+ 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

+ Details

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: 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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

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

- Definition

The percentage of amortization of the carrying value of debt instrument in year one.

+ References

No definition available.

+ Details

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

- Definition

The percentage of amortization of the carrying value of the debt instrument in the fourth and fifth fiscal year following the latest fiscal year.

+ References

No definition available.

+ Details

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

- Definition

The percentage of amortization of the carrying value of the debt instrument in the second and third fiscal year following the latest fiscal yea

+ References

No definition available.

+ Details

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

- 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

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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

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

- Definition

Represents the required scheduled payment of debt.

+ References

No definition available.

+ Details

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

- Details

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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LetterOfCreditMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=wts_SeniorNotes5.05PercentDue2020Member
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_LineOfCreditMember
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Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=wts_EurocurrencyRateLoansMember
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- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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Financing Arrangements - Credit Agreement (Details) - USD ($) $ in Millions			1 Months Ended	12 Months Ended
	Feb. 12, 2016	Jun. 18, 2010	Feb. 29, 2016	Dec. 31, 2018	Dec. 31, 2017
Credit Agreement
Borrowings outstanding				$ 355.0	$ 499.5
Stand-by letters of credit outstanding				25.8	25.7
Term Loan due February 2021
Credit Agreement
Borrowings outstanding				$ 255.0	277.5
Letters of credit
Credit Agreement
Term of debt				1 year
5.05% Senior notes due 2020
Credit Agreement
Amount drawn		$ 75.0
Borrowings outstanding				$ 75.0	$ 75.0
Interest rate (as a percent)				5.05%
Credit Agreement
Credit Agreement
Term of debt	5 years
Sublimit on letters of credit	$ 100.0
Unused and available credit under the credit agreement				$ 449.2
Stand-by letters of credit outstanding				$ 25.8
Eurocurrency rate loans \| LIBOR \| Minimum
Credit Agreement
Interest rate added to base rate (as a percent)				0.975%
Eurocurrency rate loans \| LIBOR \| Maximum
Credit Agreement
Interest rate added to base rate (as a percent)				1.45%
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 \| LIBOR \| Minimum
Credit Agreement
Interest rate added to base rate (as a percent)				0.00%
Base rate loans and swing line loans \| LIBOR \| Maximum
Credit Agreement
Interest rate added to base rate (as a percent)				0.45%
Base rate loans and swing line loans \| Federal funds
Credit Agreement
Interest rate added to base rate (as a percent)				0.50%
Senior unsecured revolving credit facility
Credit Agreement
Borrowing capacity	$ 500.0
Amount drawn				$ 25.0
Interest rate on revolving credit facility (as a percent)				3.50%
Term loan facility \| Term Loan due February 2021
Credit Agreement
Term of debt	5 years
Face amount	$ 300.0
Interest rate on term loan facility (as a percent)				3.86%
First year (as a percent)	0.00%
Second and third years (as a percent)	7.50%
Fourth and fifth years (as a percent)	10.00%
Amount drawn			$ 300.0
Required payment				$ 22.5
Term loan facility \| LIBOR \| Minimum \| Term Loan due February 2021
Credit Agreement
Interest rate added to base rate (as a percent)				1.125%
Term loan facility \| LIBOR \| Maximum \| Term Loan due February 2021
Credit Agreement
Interest rate added to base rate (as a percent)				1.75%