Basis of Presentation and Summary of Significant Accounting Policies - Gains (Losses) on Foreign Exchange Contracts (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 27, 2025	Sep. 28, 2024	Sep. 27, 2025	Sep. 28, 2024
Cost of Sales [Member] \| Foreign Currency Exchange Contract [Member]
Derivative [Line Items]
Realized (losses) gains on closed contracts	$ (23)	$ (138)	$ (1,421)	$ 914
Unrealized (losses) gains on open contracts	(922)	(26)	(618)	39
Cumulative net pre-tax gains (losses)	(945)	(164)	(2,039)	953
Interest Income [Member] \| Cross Currency Interest Rate Contract [Member]
Derivative [Line Items]
Interest earned	3,076	2,486	8,145	7,613
Interest Income [Member] \| Interest Rate Swaps Cash Flow Hedges [Member]
Derivative [Line Items]
Interest earned	120	366	431	940
Other comprehensive income [Member] \| Cross Currency Interest Rate Contract [Member]
Derivative [Line Items]
Unrealized (losses) gains on open contracts	471	(28,339)	(82,917)	(6,775)
Other comprehensive income [Member] \| Interest Rate Swaps Cash Flow Hedges [Member]
Derivative [Line Items]
Unrealized (losses) gains on open contracts	$ (32)	$ (3,391)	$ (2,163)	$ (731)

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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A

+ Details

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

- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

+ Details

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

- Definition

Aggregate impact of foreign currency derivatives on earnings for the period. Includes impact of foreign currency cash flow hedge ineffectiveness and the ineffectiveness of fair value hedging derivatives and full change in fair value of the foreign currency derivatives not designated as hedging instruments.

+ References

+ Details

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

- Definition

Aggregate impact of foreign currency derivatives closed during the period on earnings for the period.

+ References

No definition available.

+ Details

Name:	wat_RealizedGainLossOnForeignCurrencyDerivativesRecordedInEarningsNet
Namespace Prefix:	wat_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Aggregate impact of foreign currency derivatives at the end of the period on earnings for the period.

+ References

No definition available.

+ Details

Name:	wat_UnrealizedGainsOnForeignCurrencyDerivativesRecordedInEarningsNet
Namespace Prefix:	wat_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	wat_IncomeStatementLocationOneAxis=us-gaap_CostOfSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	wat_IncomeStatementLocationOneAxis=us-gaap_InterestIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CrossCurrencyInterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=wat_InterestRateSwapsCashFlowHedgesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherComprehensiveIncomeLocationAxis=us-gaap_OtherComprehensiveIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: