2.2.0.7 true Stock-Based Compensation (Details) (USD $) 40800 - Disclosure - Stock-Based Compensation (Details) true false In Thousands, except Per Share data, unless otherwise specified false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 3 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 4 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 5 USD true false false false Cost of sales [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_CostOfSalesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 6 USD true false false false Cost of sales [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_CostOfSalesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 7 USD true false false false Cost of sales [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_CostOfSalesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 8 USD true false false false Cost of sales [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_CostOfSalesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 9 USD true false false false Selling and administrative expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_SellingAndAdministrativeExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 10 USD true false false false Selling and administrative expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_SellingAndAdministrativeExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 11 USD true false false false Selling and administrative expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_SellingAndAdministrativeExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 12 USD true false false false Selling and administrative expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_SellingAndAdministrativeExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 13 USD true false false false Research and development expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_ResearchAndDevelopmentExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 14 USD true false false false Research and development expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_ResearchAndDevelopmentExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 15 USD true false false false Research and development expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_ResearchAndDevelopmentExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 16 USD true false false false Research and development expenses [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_ResearchAndDevelopmentExpensesMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 17 true false false false Inventory [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_InventoryMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember false 18 true false false false Inventory [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi wat_InventoryMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember false 19 USD true false false false Capitalized software [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_SoftwareDevelopmentMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 20 USD true false false false Capitalized software [Member] us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_SoftwareDevelopmentMember us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsByReportLineAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 21 USD true false false false Restricted Stock Plan [Member] us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis xbrldi http://xbrl.org/2006/xbrldi wat_RestrictedStockPlanMember us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 22 USD true false false false Restricted Stock Unit Plan [Member] us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis xbrldi http://xbrl.org/2006/xbrldi wat_RestrictedStockUnitPlanMember us-gaap_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAwardTypeAndPlanNameAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ 3 Stock-Based Compensation Allocation of Recognized Period Expense [Line Items] 1 us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:stringItemType string 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. false 4 Allocated stock-based compensation expense 2 us-gaap_AllocatedShareBasedCompensationExpense us-gaap true debit duration No definition available. false false false false false false false false false false false false 1 true true false false 6244000 6244 false false false 2 true true false false 7251000 7251 false false false 3 true true false false 18558000 18558 false false false 4 true true false false 21757000 21757 false false false 5 true true false false 623000 623 true false false 6 true true false false 687000 687 true false false 7 true true false false 1852000 1852 true false false 8 true true false false 2122000 2122 true false false 9 true true false false 4829000 4829 true false false 10 true true false false 5467000 5467 true false false 11 true true false false 14364000 14364 true false false 12 true true false false 16992000 16992 true false false 13 true true false false 792000 792 true false false 14 true true false false 1097000 1097 true false false 15 true true false false 2342000 2342 true false false 16 true true false false 2643000 2643 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:monetaryItemType monetary Represents the expense recognized during the period arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph g(1) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F false 5 Stock-based compensation expense capitalized 2 wat_StockBasedCompensationExpenseCapitalized wat false debit instant Represents the compensation cost capitalized as of the balance sheet date arising from share-based compensation arrangements... false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false true false false 3000000 3000000 true false false 20 false true false false 3000000 3000000 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:monetaryItemType monetary Represents the compensation cost capitalized as of the balance sheet date arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. No authoritative reference available. false 6 Stock-based compensation expense capitalized, less than $1 million 2 wat_StockBasedCompensationExpenseCapitalizedLessThan1Million wat false na instant Represents the compensation cost capitalized as of the balance sheet date arising from share-based compensation arrangements... false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 less than $1 million less than $1 million true false false 18 false false false false 0 0 less than $1 million less than $1 million true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:stringItemType string Represents the compensation cost capitalized as of the balance sheet date arising from share-based compensation arrangements (for example, shares of stock, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees, where the balance is less than $1 million. No authoritative reference available. false 8 Stock-Based Compensation by Award [Line Items] 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:stringItemType string 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. false 9 Unvested shares at beginning of period 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber us-gaap true na instant No definition available. false false false false false false false false true false false periodstartlabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false true false false 783000 783 true false false xbrli:sharesItemType shares The number of outstanding awards on nonstock option plans (for example, phantom stock plan, stock appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(b) false 10 Shares granted 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false true false false 12000 12 true false false 22 false true false false 217000 217 true false false xbrli:sharesItemType shares The number of shares issuable under a share-based award plan pertaining to grants made during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(c) false 11 Shares vested 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false true false false -216000 -216 true false false xbrli:sharesItemType shares The decrease in the number of shares potentially issuable under a share-based award plan pertaining to awards for which the grantee has gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(d) false 12 Shares forfeited 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod us-gaap true na duration No definition available. false false false false false false false false false false false totallabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false true false false -25000 -25 true false false xbrli:sharesItemType shares The number of shares under a share-based award plan other than a stock option plan that were settled during the reporting period due to a failure to satisfy vesting conditions pertaining to all option plans. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(e) true 13 Unvested shares at end of period 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber us-gaap true na instant No definition available. false false false false false false false false false true false periodendlabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false true false false 759000 759 true false false xbrli:sharesItemType shares The number of outstanding awards on nonstock option plans (for example, phantom stock plan, stock appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(b) false 14 Weighted-average grant date fair value of shares unvested at beginning of period 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue us-gaap true na instant No definition available. false false false false false false false false true false false periodstartlabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 true true false false 45.30 45.30 true false false us-types:perShareItemType decimal The weighted average fair value of nonvested awards on share-based plans excluding option plans (for example, phantom stock plan, stock appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(b) false 15 Weighted-average grant date fair value of shares granted 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap true na duration No definition available. false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 true true false false 61.63 61.63 true false false 22 true true false false 62.24 62.24 true false false us-types:perShareItemType decimal The weighted average fair value at grant for nonvested share-based awards issued during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(c) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph c(1) false 16 Weighted-average grant date fair value of shares vested 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue us-gaap true na duration No definition available. false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 true true false false 46.97 46.97 true false false us-types:perShareItemType decimal The weighted average fair value as of grant dates pertaining to a share-based award plan other than a stock option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(d) false 17 Weighted-average grant date fair value of shares forfeited 2 wat_WeightedAverageGrantDateFairValueOfSharesForfeited wat false na duration The weighted average fair value as of the grant date of share-based award plans other than stock option plans that were not... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 true true false false 47.67 47.67 true false false us-types:perShareItemType decimal The weighted average fair value as of the grant date of share-based award plans other than stock option plans that were not exercised or put into effect during the reporting period as a result of the occurrence of a terminating event specified in the contractual agreement of the plan. No authoritative reference available. false 18 Weighted-average grant date fair value of shares unvested at end of period 2 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue us-gaap true na instant No definition available. false false false false false false false false false true false periodendlabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 true true false false 49.59 49.59 true false false us-types:perShareItemType decimal The weighted average fair value of nonvested awards on share-based plans excluding option plans (for example, phantom stock plan, stock appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(2)(b) false 19 Stock Option Fair Value Assumptions and Methodology [Abstract] 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 20 Stock option fair value assumptions, risk free interest rate 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.03 0.03 false false false 4 false true false false 0.02 0.02 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:percentItemType pure The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(d) false 21 Stock option fair value assumptions, expected life in years 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 6 6 false false false 4 false true false false 6 6 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:decimalItemType decimal The period of time a share-based award is expected to be outstanding. A share-based award's expected term shall be determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior. An entity is required to aggregate individual awards into relatively homogeneous groups. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section D -Subsection 2 false 22 Stock option fair value assumptions, expected volatility 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 0.293 0.293 false false false 4 false true false false 0.57 0.57 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:percentItemType pure The estimated measure of the percentage amount by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(b) false 23 Stock option fair value assumptions, expected dividends 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments us-gaap true debit duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0     false false false 4 false false false false 0 0     false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:monetaryItemType monetary The estimated amount of dividends to be paid to holders of the underlying shares (expected dividends) over the option's term. Dividends are taken into account because payment of dividends to shareholders reduces the fair value of the underlying shares, and option holders generally do not receive dividends. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(c) false 24 Weighted-average grant date fair value of options granted 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue us-gaap true na duration No definition available. false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 21.40 21.40 false false false 4 true true false false 20.71 20.71 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph c(1) false 25 Stock Options Outstanding Roll Forward [Abstract] 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:stringItemType string A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. false 26 Options outstanding at beginning of period 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber us-gaap true na instant No definition available. false false false false false false false false true false false periodstartlabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 6857000 6857 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:sharesItemType shares The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance-sheet date, including vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(b) false 27 Options granted 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 32000 32 false false false 4 false true false false 28000 28 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:sharesItemType shares The quantity of shares issuable on stock options awarded under the plan during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(d) false 28 Options exercised 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriod us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false -648000 -648 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:sharesItemType shares The decrease in the number of reserved shares that could potentially be issued attributable to the exercise or conversion during the reporting period of previously issued stock options under the option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(e) false 29 Options canceled 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod us-gaap true na duration No definition available. false false false false false false false false false false false totallabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false -26000 -26 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:sharesItemType shares For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired. No authoritative reference available. true 30 Options outstanding at end of period 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber us-gaap true na instant No definition available. false false false false false false false false false true false periodendlabel false 1 false true false false 6215000 6215 false false false 2 false false false false 0 0 false false false 3 false true false false 6215000 6215 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false xbrli:sharesItemType shares The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance-sheet date, including vested options. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(a) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(b) false 31 Weighted-average exercise price of options outstanding at beginning of period 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice us-gaap true na instant No definition available. false false false false false false false false true false false periodstartlabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 47.58 47.58 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(a) false 32 Weighted-average exercise price of options granted 1 wat_WeightedAverageExercisePriceOfOptionsGranted wat false na duration The weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded under the... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 61.63 61.63 false false false 4 true true false false 38.09 38.09 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period. No authoritative reference available. false 33 Weighted-average exercise price of options exercised 1 wat_WeightedAverageExercisePriceOfOptionsExercised wat false na duration The weighted average price at which option holders acquired shares when converting their stock options into shares under the... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 37.61 37.61 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period. No authoritative reference available. false 34 Weighted average exercise price of options canceled 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice us-gaap true na duration No definition available. false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 71.93 71.93 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal For presentations that combine terminations, the weighted average price of expired options and the price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncompliance with plan terms during the reporting period . No authoritative reference available. false 35 Weighted-average exercise price of options outstanding at end of period 1 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice us-gaap true na instant No definition available. false false false false false false false false false true false periodendlabel true 1 true true false false 48.59 48.59 false false false 2 false false false false 0 0 false false false 3 true true false false 48.59 48.59 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph b(1)(a) false 36 Exercise price range of options outstanding at beginning of period, lower range limit 1 wat_ExercisePriceRangeOfOptionsOutstandingLowerRangeLimit wat false na instant The floor of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock option... false false false false false false false false true false false periodstartlabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 21.05 21.05 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The floor of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock option plan. No authoritative reference available. false 37 Exercise price range of options outstanding at beginning of period, upper range limit 1 wat_ExercisePriceRangeOfOptionsOutstandingUpperRangeLimit wat false na instant The ceiling of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock... false false false false false false false false true false false periodstartlabel true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 80.97 80.97 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The ceiling of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock option plan. No authoritative reference available. false 38 Exercise price range of options exercised, lower range limit 1 wat_ExercisePriceRangeOfOptionsExercisedLowerRangeLimit wat false na duration The floor of a range of exercise prices at which option holders acquired shares when converting their stock options into... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 21.39 21.39 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The floor of a range of exercise prices at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period. No authoritative reference available. false 39 Exercise price range of options exercised, upper range limit 1 wat_ExercisePriceRangeOfOptionsExercisedUpperRangeLimit wat false na duration The ceiling of a range of exercise prices at which option holders acquired shares when converting their stock options into... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 72.06 72.06 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The ceiling of a range of exercise prices at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period. No authoritative reference available. false 40 Exercise price range of options canceled, lower range limit 1 wat_ExercisePriceRangeOfOptionsCanceledLowerRangeLimit wat false na duration For presentations that combine terminations, the floor of a range of the price of expired options and the price at which... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 49.31 49.31 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal For presentations that combine terminations, the floor of a range of the price of expired options and the price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncomplia nce with plan terms during the reporting period . No authoritative reference available. false 41 Exercise price range of options canceled, upper range limit 1 wat_ExercisePriceRangeOfOptionsCanceledUpperRangeLimit wat false na duration For presentations that combine terminations, the ceiling of a range of the price of expired options and the price at which... false false false false false false false false false false false true 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 72.06 72.06 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal For presentations that combine terminations, the ceiling of a range of the price of expired options and the price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncomplia nce with plan terms during the reporting period . No authoritative reference available. false 42 Exercise price range of options outstanding at end of period, lower range limit 1 wat_ExercisePriceRangeOfOptionsOutstandingLowerRangeLimit wat false na instant The floor of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock option... false false false false false false false false false true false periodendlabel true 1 true true false false 21.05 21.05 false false false 2 false false false false 0 0 false false false 3 true true false false 21.05 21.05 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The floor of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock option plan. No authoritative reference available. false 43 Exercise price range of options outstanding at end of period, upper range limit 1 wat_ExercisePriceRangeOfOptionsOutstandingUpperRangeLimit wat false na instant The ceiling of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock... false false false false false false false false false true false periodendlabel true 1 true true false false 80.97 80.97 false false false 2 false false false false 0 0 false false false 3 true true false false 80.97 80.97 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false 16 false false false false 0 0 true false false 17 false false false false 0 0 true false false 18 false false false false 0 0 true false false 19 false false false false 0 0 true false false 20 false false false false 0 0 true false false 21 false false false false 0 0 true false false 22 false false false false 0 0 true false false us-types:perShareItemType decimal The ceiling of a range of exercise prices at which grantees can acquire the shares reserved for issuance under the stock option plan. No authoritative reference available. false 22 40 false Thousands Thousands NoRounding true true