Basis of Presentation and Summary of Significant Accounting Policies (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		6 Months Ended				6 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011	Dec. 31, 2011	May 09, 2012 May 2012 Program [Member]	Jun. 30, 2012 Programs authorized by Board of Directors [Member]	Jul. 02, 2011 Programs authorized by Board of Directors [Member]	Jun. 30, 2012 Related to the Vesting of Restricted Stock Units [Member]	Jul. 02, 2011 Related to the Vesting of Restricted Stock Units [Member]	Jun. 30, 2012 Unsecured debt [Member]	Dec. 31, 2011 Unsecured debt [Member]	Jun. 30, 2012 Held by foreign subsidiaries [Member]	Dec. 31, 2011 Held by foreign subsidiaries [Member]	Jun. 30, 2012 Significant Other Observable Inputs (Level 2)	Dec. 31, 2011 Significant Other Observable Inputs (Level 2)
Fair Value of Assets and Liabilities Measured on a Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 126,515,000		$ 126,515,000		$ 142,966,000										$ 126,515,000	$ 142,966,000
Short-term investments	1,022,708,000		1,022,708,000		897,361,000										1,022,708,000	897,361,000
Waters 401(k) Restoration Plan assets	22,560,000		22,560,000		20,667,000										22,560,000	20,667,000
Foreign currency exchange contract agreements, assets	209,000		209,000		81,000										209,000	81,000
Fair value of total assets measured on a recurring basis	1,171,992,000		1,171,992,000		1,061,075,000										1,171,992,000	1,061,075,000
Foreign currency exchange contract agreements, liabilities	1,188,000		1,188,000		1,317,000										1,188,000	1,317,000
Fair value of total liabilities measured on a recurring basis	1,188,000		1,188,000		1,317,000										1,188,000	1,317,000
Cash, Cash Equivalents and Short-Term Investments [Line Items]
Cash, cash equivalents and short-term investments	1,392,000,000		1,392,000,000		1,281,000,000								1,354,000,000	1,200,000,000
Cash equivalents description			The Company’s cash equivalents primarily represent highly liquid investments, with original maturities of 90 days or less, primarily in bank deposits, U.S. and U.K. treasury bill money market funds and commercial paper.
Debt [Line Items]
Long-term debt	700,000,000		700,000,000		700,000,000						400,000,000	400,000,000
Fair value of debt instruments											413,000,000	410,000,000
Stock Repurchase Program [Line Items]
Stock repurchase program authorization amount						750,000,000
Treasury stock shares acquired							2.0	1.7
Treasury stock							165,000,000	148,000,000	6,000,000	6,000,000
Stock repurchase program period, in years						2
Stock repurchase program remaining amount authorized for future purchases							771,000,000
Summary of Derivative Instruments by Risk Exposure [Abstract]
Notional amount of forward foreign exchange contracts	134,000,000		134,000,000		161,000,000
Forward foreign exchange contract assets	209,000		209,000		81,000										209,000	81,000
Forward foreign exchange contract liabilities	1,188,000		1,188,000		1,317,000										1,188,000	1,317,000
Cumulative net pre-tax gains (losses) on forward foreign exchange contracts	(3,530,000)	(1,676,000)	733,000	2,121,000
Gain (loss) on closed forward foreign exchange contracts	(3,500,000)	(922,000)	475,000	1,970,000
Change in unrealized gain (loss) on open forward foreign exchange contracts	(30,000)	(754,000)	258,000	151,000
Maturity period of forward foreign exchange contracts	The periods of these forward contracts typically range from one to three months and have varying notional amounts, which are intended to be consistent with changes in the underlying exposures.		The periods of these forward contracts typically range from one to three months and have varying notional amounts, which are intended to be consistent with changes in the underlying exposures.
Warranty Accrual Roll Forward [Abstract]
Accrued warranty liability, balance at beginning of period			13,258,000	11,272,000
Accruals for warranties			2,808,000	4,835,000
Settlements made			(3,813,000)	(3,808,000)
Accrued warranty liability, balance at end of period	$ 12,253,000	$ 12,299,000	$ 12,253,000	$ 12,299,000