Basis of Presentation and Summary of Significant Accounting Policies (Details) (USD $) Share data in Millions	3 Months Ended		6 Months Ended									6 Months Ended		27 Months Ended		6 Months Ended
	Jul. 02, 2011	Jul. 03, 2010	Jul. 02, 2011	Jul. 03, 2010	Dec. 31, 2010	Jul. 02, 2011 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member]	Jul. 02, 2011 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member]	Jul. 02, 2011 Unsecured debt [Member]	Dec. 31, 2010 Unsecured debt [Member]	Jul. 02, 2011 February 2009 Program [Member]	Jul. 03, 2010 February 2009 Program [Member]	Apr. 02, 2011 February 2009 Program [Member]	Feb. 27, 2009 February 2009 Program [Member]	Jul. 02, 2011 February 2011 Program [Member]	Feb. 16, 2011 February 2011 Program [Member]
Fair Value of Assets Measured on a Recurring Basis [Line Items]
Cash equivalents	$ 138,248,000		$ 138,248,000		$ 87,975,000	$ 138,248,000	$ 87,975,000
Short-term investments	776,763,000		776,763,000		637,921,000	776,763,000	637,921,000
Waters 401(k) Restoration Plan assets	22,026,000		22,026,000		19,988,000	22,026,000	19,988,000
Foreign currency exchange contract agreements, assets	389,000		389,000		424,000	389,000	424,000
Fair value of total assets measured on a recurring basis	937,426,000		937,426,000		746,308,000	937,426,000	746,308,000
Fair Value of Liabilities Measured on a Recurring Basis [Line Items]
Foreign currency exchange contract agreements, liabilities	440,000		440,000		626,000			440,000	626,000
Fair value of total liabilities measured on a recurring basis	440,000		440,000		626,000			440,000	626,000
Debt [Line Items]
Long-term debt	700,000,000		700,000,000		700,000,000					400,000,000	200,000,000
Fair value of debt instruments										395,000,000	203,000,000
Stock Repurchase Program [Line Items]
Stock repurchase program authorization amount															500,000,000		500,000,000
Treasury stock shares acquired												0.7	2.7	8.2		1.0
Treasury stock			148,000,000									50,000,000	176,000,000	499,000,000		98,000,000
Summary of Derivative Instruments by Risk Exposure [Abstract]
Notional amount of forward foreign exchange contracts	144,000,000		144,000,000		136,000,000
Forward foreign exchange contract assets	389,000		389,000		424,000	389,000	424,000
Forward foreign exchange contract liabilities	440,000		440,000		626,000			440,000	626,000
Cumulative net pre-tax gains (losses) on forward foreign exchange contracts	(1,676,000)	(4,465,000)	2,121,000	(6,710,000)
Gain (loss) on closed forward foreign exchange contracts	(922,000)	(3,336,000)	1,970,000	(6,967,000)
Change in unrealized gain (loss) on open forward foreign exchange contracts	(754,000)	(1,129,000)	151,000	257,000
Warranty Accrual Roll Forward [Abstract]
Accrued warranty liability, balance at beginning of period			11,272,000	10,109,000
Accruals for warranties			4,835,000	3,001,000
Settlements made			(3,808,000)	(2,836,000)
Accrued warranty liability, balance at end of period	$ 12,299,000	$ 10,274,000	$ 12,299,000	$ 10,274,000