1.0.0.3 false Consolidated Statements of Operations (USD $) In Thousands, except Per Share data false 1 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 2 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 3 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 5 Product sales 3 us-gaap_SalesRevenueGoodsNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 1051978000 1051978 false false 2 true true 1139886000 1139886 false false 3 true true 1087592000 1087592 false false No definition available. No authoritative reference available. false 6 Service sales 3 us-gaap_SalesRevenueServicesNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 446722000 446722 false false 2 false true 435238000 435238 false false 3 false true 385456000 385456 false false No definition available. No authoritative reference available. true 7 Total net sales 3 us-gaap_SalesRevenueNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 1498700000 1498700 false false 2 false true 1575124000 1575124 false false 3 false true 1473048000 1473048 false false No definition available. No authoritative reference available. false 8 Cost of product sales 3 us-gaap_CostOfGoodsSold us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 406681000 406681 false false 2 false true 457886000 457886 false false 3 false true 441877000 441877 false false No definition available. No authoritative reference available. false 9 Cost of service sales 3 us-gaap_CostOfServices us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 188201000 188201 false false 2 false true 203380000 203380 false false 3 false true 189245000 189245 false false No definition available. No authoritative reference available. true 10 Total cost of sales 3 us-gaap_CostOfGoodsAndServicesSold us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 594882000 594882 false false 2 false true 661266000 661266 false false 3 false true 631122000 631122 false false No definition available. No authoritative reference available. true 11 Gross profit 3 us-gaap_GrossProfit us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 903818000 903818 false false 2 false true 913858000 913858 false false 3 false true 841926000 841926 false false No definition available. No authoritative reference available. false 12 Selling and administrative expenses 3 us-gaap_SellingGeneralAndAdministrativeExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 421403000 421403 false false 2 false true 426699000 426699 false false 3 false true 403703000 403703 false false No definition available. No authoritative reference available. false 13 Research and development expenses 3 us-gaap_ResearchAndDevelopmentExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 77154000 77154 false false 2 false true 81588000 81588 false false 3 false true 80649000 80649 false false No definition available. No authoritative reference available. false 14 Purchased intangibles amortization 3 wat_PurchasedIntangiblesAmortization wat false debit duration monetary Purchased intangibles amortization false false false false false false false false false 1 false true 10659000 10659 false false 2 false true 9290000 9290 false false 3 false true 8695000 8695 false false Purchased intangibles amortization No authoritative reference available. false 15 Litigation provisions (Note 10) 3 wat_LitigationProvisionsNote10 wat false debit duration monetary Litigation provisions (Note 10) false false false false false false false false false 1 false true 0 0 false false 2 false true 6527000 6527 false false 3 false true 0 0 false false Litigation provisions (Note 10) No authoritative reference available. true 16 Operating income 3 us-gaap_OperatingIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 394602000 394602 false false 2 false true 389754000 389754 false false 3 false true 348879000 348879 false false No definition available. No authoritative reference available. false 17 Interest expense 3 us-gaap_InterestExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -10986000 -10986 false false 2 false true -38521000 -38521 false false 3 false true -56515000 -56515 false false No definition available. No authoritative reference available. false 18 Interest income 3 us-gaap_InvestmentIncomeInterest us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 3036000 3036 false false 2 false true 20959000 20959 false false 3 false true 30828000 30828 false false No definition available. No authoritative reference available. true 19 Income from operations before income taxes 3 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 386652000 386652 false false 2 false true 372192000 372192 false false 3 false true 323192000 323192 false false No definition available. No authoritative reference available. false 20 Provision for income taxes 3 us-gaap_IncomeTaxExpenseBenefit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 63339000 63339 false false 2 false true 49713000 49713 false false 3 false true 55120000 55120 false false No definition available. No authoritative reference available. true 21 Net income 3 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 323313000 323313 false false 2 true true 322479000 322479 false false 3 true true 268072000 268072 false false No definition available. No authoritative reference available. true 22 Net income per basic common share 3 us-gaap_EarningsPerShareBasic us-gaap true na duration decimal No definition available. false false false false false false false false true 1 true true 3.37 3.37 false false 2 true true 3.25 3.25 false false 3 true true 2.67 2.67 false false No definition available. No authoritative reference available. false 23 Weighted-average number of basic common shares 3 us-gaap_WeightedAverageNumberOfSharesOutstandingBasic us-gaap true na duration shares No definition available. false false false false false false false false false 1 false true 95797000 95797 false false 2 false true 99199000 99199 false false 3 false true 100500000 100500 false false No definition available. No authoritative reference available. false 24 Net income per diluted common share 3 us-gaap_EarningsPerShareDiluted us-gaap true na duration decimal No definition available. false false false false false false false false true 1 true true 3.34 3.34 false false 2 true true 3.21 3.21 false false 3 true true 2.62 2.62 false false No definition available. No authoritative reference available. false 25 Weighted-average number of diluted common shares and equivalents 3 us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding us-gaap true na duration shares No definition available. false false false false false false false false false 1 false true 96862000 96862 false false 2 false true 100555000 100555 false false 3 false true 102505000 102505 false false No definition available. No authoritative reference available. false false 3 21 false Thousands Thousands Hundreds false true