1.0.0.3 false Consolidated Statements of Operations (unaudited) (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 false 4 $ 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 259532000 259532 false false 2 true true 277717000 277717 false false 3 true true 740501000 740501 false false 4 true true 835303000 835303 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 114431000 114431 false false 2 false true 108593000 108593 false false 3 false true 329351000 329351 false false 4 false true 321490000 321490 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 373963000 373963 false false 2 false true 386310000 386310 false false 3 false true 1069852000 1069852 false false 4 false true 1156793000 1156793 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 104038000 104038 false false 2 false true 109278000 109278 false false 3 false true 285946000 285946 false false 4 false true 336874000 336874 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 49105000 49105 false false 2 false true 49242000 49242 false false 3 false true 138805000 138805 false false 4 false true 152329000 152329 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 153143000 153143 false false 2 false true 158520000 158520 false false 3 false true 424751000 424751 false false 4 false true 489203000 489203 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 220820000 220820 false false 2 false true 227790000 227790 false false 3 false true 645101000 645101 false false 4 false true 667590000 667590 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 102675000 102675 false false 2 false true 107463000 107463 false false 3 false true 311417000 311417 false false 4 false true 325235000 325235 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 19310000 19310 false false 2 false true 19946000 19946 false false 3 false true 57364000 57364 false false 4 false true 61960000 61960 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 2723000 2723 false false 2 false true 2349000 2349 false false 3 false true 8022000 8022 false false 4 false true 6973000 6973 false false Purchased intangibles amortization No authoritative reference available. true 15 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 96112000 96112 false false 2 false true 98032000 98032 false false 3 false true 268298000 268298 false false 4 false true 273422000 273422 false false No definition available. No authoritative reference available. false 16 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 -2864000 -2864 false false 2 false true -10570000 -10570 false false 3 false true -8643000 -8643 false false 4 false true -31534000 -31534 false false No definition available. No authoritative reference available. false 17 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 785000 785 false false 2 false true 6028000 6028 false false 3 false true 2288000 2288 false false 4 false true 17893000 17893 false false No definition available. No authoritative reference available. true 18 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 94033000 94033 false false 2 false true 93490000 93490 false false 3 false true 261943000 261943 false false 4 false true 259781000 259781 false false No definition available. No authoritative reference available. false 19 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 18097000 18097 false false 2 false true 21987000 21987 false false 3 false true 42753000 42753 false false 4 false true 36655000 36655 false false No definition available. No authoritative reference available. true 20 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 75936000 75936 false false 2 true true 71503000 71503 false false 3 true true 219190000 219190 false false 4 true true 223126000 223126 false false No definition available. No authoritative reference available. true 21 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 0.8 0.8 false false 2 true true 0.72 0.72 false false 3 true true 2.28 2.28 false false 4 true true 2.24 2.24 false false No definition available. No authoritative reference available. false 22 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 95235000 95235 false false 2 false true 98891000 98891 false false 3 false true 96215000 96215 false false 4 false true 99611000 99611 false false No definition available. No authoritative reference available. false 23 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 0.79 0.79 false false 2 true true 0.71 0.71 false false 3 true true 2.26 2.26 false false 4 true true 2.21 2.21 false false No definition available. No authoritative reference available. false 24 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 96513000 96513 false false 2 false true 100566000 100566 false false 3 false true 97027000 97027 false false 4 false true 101150000 101150 false false No definition available. No authoritative reference available. false false 4 20 false Thousands Thousands Hundreds false true