Business Segment Information (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2011	Oct. 02, 2010	Oct. 01, 2011	Oct. 02, 2010
Entity-Wide Revenue from External Customers [Line Items]
Product sales	$ 321,348	$ 282,934	$ 940,834	$ 811,401
Service sales	133,186	118,104	388,930	348,392
Total net sales	454,534	401,038	1,329,764	1,159,793
Waters instrument systems [Member]
Entity-Wide Revenue from External Customers [Line Items]
Product sales	212,664	185,526	616,596	526,627
Chemistry [Member]
Entity-Wide Revenue from External Customers [Line Items]
Product sales	72,104	65,595	220,125	195,144
TA instrument systems [Member]
Entity-Wide Revenue from External Customers [Line Items]
Product sales	36,580	31,813	104,113	89,630
Waters service [Member]
Entity-Wide Revenue from External Customers [Line Items]
Service sales	121,245	107,904	354,523	317,798
TA service [Member]
Entity-Wide Revenue from External Customers [Line Items]
Service sales	$ 11,941	$ 10,200	$ 34,407	$ 30,594