Operating Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 segment	Sep. 30, 2011
Financial information of reportable segments
Number of operating units			15
Number of reportable segments			6
Net sales	$ 3,023.3	$ 1,736.1	$ 8,792.9	$ 4,953.2
Operating Income	401.2	239.6	893.5	589.6
Subtotal at fixed currency rates
Financial information of reportable segments
Net sales	3,043.7	1,670.8	8,768.9	4,809.0
Operating Income	403.0	231.3	892.0	573.9
U.S. Cleaning and Sanitizing
Financial information of reportable segments
Net sales	774.1	763.1	2,243.9	2,197.0
Operating Income	183.9	157.7	482.6	412.6
U.S. Other Services
Financial information of reportable segments
Net sales	124.2	119.6	357.1	343.3
Operating Income	21.6	20.9	53.9	51.5
Int'l Cleaning, Sanitizing & Other Services
Financial information of reportable segments
Net sales	813.5	788.1	2,342.7	2,268.7
Operating Income	96.8	86.1	227.3	199.5
Global Water
Financial information of reportable segments
Net sales	542.9		1,551.2
Operating Income	69.8		167.6
Global Paper
Financial information of reportable segments
Net sales	202.4		602.2
Operating Income	23.7		60.7
Global Energy
Financial information of reportable segments
Net sales	586.6		1,671.8
Operating Income	94.2		257.4
Corporate
Financial information of reportable segments
Operating Income	(87.0)	(33.4)	(357.5)	(89.7)
Currency impact
Financial information of reportable segments
Net sales	(20.4)	65.3	24.0	144.2
Operating Income	$ (1.8)	$ 8.3	$ 1.5	$ 15.7
Nalco
Financial information of reportable segments
Number of operating units			3