Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
Oct. 01, 2011
Basis of Presentation and Summary of Significant Accounting Policies (Policies) [Abstract]
Nature of Operations	Waters Corporation (“Waters®” or the “Company”), an analytical instrument manufacturer, primarily designs, manufactures, sells and services, through its Waters Division, high performance liquid chromatography (“HPLC”), ultra performance liquid chromatography (“UPLC®” and together with HPLC, referred to as “LC”) and mass spectrometry (“MS”) instrument systems and support products, including chromatography columns, other consumable products and comprehensive post-warranty service plans. These systems are complementary products that can be integrated together and used along with other analytical instruments. LC is a standard technique and is utilized in a broad range of industries to detect, identify, monitor and measure the chemical, physical and biological composition of materials, and to purify a full range of compounds. MS instruments are used in drug discovery and development, including clinical trial testing, the analysis of proteins in disease processes (known as “proteomics”), food safety analysis and environmental testing. LC is often combined with MS to create LC-MS instruments that include a liquid phase sample introduction and separation system with mass spectrometric compound identification and quantification. Through its TA Division (“TA®”), the Company primarily designs, manufactures, sells and services thermal analysis, rheometry and calorimetry instruments, which are used in predicting the suitability of fine chemicals, polymers and viscous liquids for various industrial products, consumer goods and healthcare products, as well as for life science research. The Company is also a developer and supplier of software-based products that interface with the Company's instruments and are typically purchased by customers as part of the instrument system.
Fiscal Period Description	The Company's interim fiscal quarter typically ends on the thirteenth Saturday of each quarter. Since the Company's fiscal year end is December 31, the first and fourth fiscal quarters will not consist of thirteen complete weeks. The Company's third fiscal quarters for 2011 and 2010 ended on October 1, 2011 and October 2, 2010, respectively.
Basis of Accounting Description	The accompanying unaudited interim consolidated financial statements have been prepared in accordance with the instructions to the Quarterly Report on Form 10-Q and do not include all of the information and note disclosures required by generally accepted accounting principles (“GAAP”) in the United States of America. It is management's opinion that the accompanying interim consolidated financial statements reflect all adjustments (which are normal and recurring) that are necessary for a fair statement of the results for the interim periods. The interim consolidated financial statements should be read in conjunction with the consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2010, as filed with the Securities and Exchange Commission on February 25, 2011.
Consolidation Policy	The consolidated financial statements include the accounts of the Company and its subsidiaries, most of which are wholly owned. All material inter-company balances and transactions have been eliminated.
Use of Estimates and Judgments	The preparation of consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities at the dates of the financial statements. Actual amounts may differ from these estimates under different assumptions or conditions.
Cash, Cash Equivalents, and Short-term Investments	Cash, Cash Equivalents and Short-Term Investments The Company's cash equivalents primarily represent highly liquid investments, with original maturities of 90 days or less, primarily in bank deposits, and AAA rated U.S. treasury, Canadian treasury, commercial paper and European government bond money market funds, which are convertible to a known amount of cash and carry an insignificant risk of change in market value. Investments with longer maturities are classified as short-term investments, and are held primarily in bank deposits and U.S., Canadian, German, French and Dutch government treasury bills.
Fair Value Measurements Policy	Fair Value Measurements In accordance with the accounting standards for fair value measurements and disclosures, certain of the Company's assets and liabilities are measured at fair value on a recurring basis as of October 1, 2011 and December 31, 2010. Fair values determined by Level 1 inputs utilize observable data, such as quoted prices in active markets. Fair values determined by Level 2 inputs utilize data points other than quoted prices in active markets that are observable either directly or indirectly. Fair values determined by Level 3 inputs utilize unobservable data points for which there is little or no market data, which require the reporting entity to develop its own assumptions. Fair Value of Other Financial Instruments The Company's cash, accounts receivable, accounts payable and variable interest rate debt are recorded at cost, which approximates fair value.
Derivatives Policy	The Company records its hedge transactions in accordance with the accounting standards for derivative instruments and hedging activities, which establish the accounting and reporting standards for derivative instruments, including certain derivative instruments embedded in other contracts, and for hedging activities. All derivatives, whether designated in hedging relationships or not, are required to be recorded on the consolidated balance sheets at fair value as either assets or liabilities. If the derivative is designated as a fair-value hedge, the changes in the fair value of the derivative and of the hedged item attributable to the hedged risk are recognized in earnings. If the derivative is designated as a cash flow hedge, the effective portions of changes in the fair value of the derivative are recorded in other comprehensive income and are recognized in earnings when the hedged item affects earnings; ineffective portions of changes in fair value are recognized in earnings. In addition, disclosures required for derivative instruments and hedging activities include the Company's objectives for using derivative instruments, the level of derivative activity the Company engages in, as well as how derivative instruments and related hedged items affect the Company's financial position and performance.
Product Warranty Policy	Product Warranty Costs The Company accrues estimated product warranty costs at the time of sale, which are included in cost of sales in the consolidated statements of operations. While the Company engages in extensive product quality programs and processes, including actively monitoring and evaluating the quality of its component supplies, the Company's warranty obligation is affected by product failure rates, material usage and service delivery costs incurred in correcting a product failure. The amount of the accrued warranty liability is based on historical information, such as past experience, prior product failure rates, number of units repaired and estimated costs of material and labor. The liability is reviewed for reasonableness at least quarterly.
Subsequent Events	Subsequent Events The Company did not have any material subsequent events.

The entire disclosure of the components of cash, cash equivalents, and short-term investments. Short-term investments may include current marketable securities.

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Disclosure of accounting policy for its derivative instruments and hedging activities. Disclosure may include: (1) Each method used to account for derivative financial instruments and derivative commodity instruments ("derivatives"); (2) the types of derivatives accounted for under each method; (3) the criteria required to be met for each accounting method used, including a discussion of the criteria required to be met for hedge or deferral accounting and accrual or settlement accounting (for example, whether and how risk reduction, correlation, designation, and effectiveness tests are applied); (4) the accounting method used if the criteria specified for hedge accounting are not met; (5) the method used to account for termination of derivatives designated as hedges or derivatives used to affect directly or indirectly the terms, fair values, or cash flows of a designated item; (6) the method used to account for derivatives when the designated item matures, is sold, is extinguished, or is terminated. In addition, the method used to account for derivatives designated to an anticipated transaction, when the anticipated transaction is no longer likely to occur; and (7) where and when derivatives, and their related gains or losses are reported in the statement of financial position, cash flows, and results of operations and (8) an accounting policy decision to offset fair value amounts with counterparties. An entity may also describe its embedded derivatives, and the method(s) used to determine the fair values of derivatives and any significant assumptions used in such valuations.

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The entire disclosure for the nature of an entity's business, the major products or services it sells or provides and its principal markets, including the locations of those markets. If the entity operates in more than one business, the disclosure also indicates the relative importance of its operations in each business and the basis for the determination (for example, assets, revenues, or earnings).

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Describes an entity's fiscal year or other fiscal period. This disclosure may include identification of the fiscal period end-date, the length of the fiscal period, any reporting period lag between the entity and its subsidiaries, or equity investees. If a reporting lag exists, the closing date of the entity having a different period end should be noted, along with an explanation of the necessity for using different closing dates. Any intervening events that materially affect the entity's financial position or results of operations also should be disclosed.

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Provides an entity's explanation that the preparation of financial statements in conformity with generally accepted accounting principles requires the use of management estimates. Estimates used in the determination of carrying amounts of assets or liabilities, or in disclosure of gain or loss contingencies should be disclosed if known information available prior to issuance of the financial statements indicates that both of these criteria are met: (1) It is at least reasonably possible that the estimate of the effect on the financial statements of a condition, situation, or set of circumstances that existed at the date of the financial statements will change in the near term (less than one year from the date of issuance) due to one or more future confirming events, and (2) The effect of the change would be material to the financial statements. The disclosure should indicate the nature of the uncertainty and include an indication that it is at least reasonably possible that a change in the estimate will occur in the near term. Disclosure of the factors that cause the estimate to be sensitive to change also is encouraged. Entities also may identify those areas that are subject to significant estimates.

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