Basis of Presentation and Summary of Significant Accounting Policies (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended					9 Months Ended		27 Months Ended		9 Months Ended
	Oct. 01, 2011	Oct. 02, 2010	Oct. 01, 2011	Oct. 02, 2010	Dec. 31, 2010	Oct. 01, 2011 Significant Other Observable Inputs (Level 2) [Member]	Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member]	Oct. 01, 2011 Unsecured debt [Member]	Dec. 31, 2010 Unsecured debt [Member]	Oct. 01, 2011 February 2009 Program [Member]	Oct. 02, 2010 February 2009 Program [Member]	Apr. 02, 2011 February 2009 Program [Member]	Feb. 27, 2009 February 2009 Program [Member]	Oct. 01, 2011 February 2011 Program [Member]	Feb. 16, 2011 February 2011 Program [Member]
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash, cash equivalents and short-term investments	$ 1,130,000,000		$ 1,130,000,000		$ 901,000,000
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, 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.		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.
Fair Value of Assets and Liabilities Measured on a Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	210,420,000		210,420,000		87,975,000	210,420,000	87,975,000
Short-term investments	770,291,000		770,291,000		637,921,000	770,291,000	637,921,000
Waters 401(k) Restoration Plan assets	19,079,000		19,079,000		19,988,000	19,079,000	19,988,000
Foreign currency exchange contract agreements, assets	218,000		218,000		424,000	218,000	424,000
Fair value of total assets measured on a recurring basis	1,000,008,000		1,000,008,000		746,308,000	1,000,008,000	746,308,000
Foreign currency exchange contract agreements, liabilities	108,000		108,000		626,000	108,000	626,000
Fair value of total liabilities measured on a recurring basis	108,000		108,000		626,000	108,000	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								408,000,000	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	3.8	8.2		2.9
Treasury stock			292,000,000							50,000,000	241,000,000	499,000,000		242,000,000
Stock repurchase program period, in years													2		2
Summary of Derivative Instruments by Risk Exposure [Abstract]
Notional amount of forward foreign exchange contracts	137,000,000		137,000,000		136,000,000
Forward foreign exchange contract assets	218,000		218,000		424,000	218,000	424,000
Forward foreign exchange contract liabilities	108,000		108,000		626,000	108,000	626,000
Cumulative net pre-tax gains (losses) on forward foreign exchange contracts	(3,781,000)	1,616,000	(1,659,000)	(5,095,000)
Gain (loss) on closed forward foreign exchange contracts	(3,941,000)	1,998,000	(1,971,000)	(4,968,000)
Change in unrealized gain (loss) on open forward foreign exchange contracts	160,000	(382,000)	312,000	(127,000)
Warranty Accrual Roll Forward [Abstract]
Accrued warranty liability, balance at beginning of period			11,272,000	10,109,000	10,109,000
Accruals for warranties			7,061,000	4,849,000
Settlements made			(5,837,000)	(4,191,000)
Accrued warranty liability, balance at end of period	$ 12,496,000	$ 10,767,000	$ 12,496,000	$ 10,767,000	$ 11,272,000