Special (Gains) and Charges (Details 2) (USD $) In Millions, unless otherwise specified			3 Months Ended	9 Months Ended		12 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended	20 Months Ended	3 Months Ended	9 Months Ended	10 Months Ended	12 Months Ended	9 Months Ended		9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended		9 Months Ended		12 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Nalco	Sep. 30, 2012 Nalco	Sep. 30, 2012 2011 Restructuring Plan and Merger Restructuring Plan	Dec. 31, 2011 2011 Restructuring Plan and Merger Restructuring Plan	Sep. 30, 2012 2011 Restructuring Plan	Sep. 30, 2011 2011 Restructuring Plan	Sep. 30, 2012 2011 Restructuring Plan position	Sep. 30, 2011 2011 Restructuring Plan	Dec. 31, 2011 2011 Restructuring Plan	Sep. 30, 2012 2011 Restructuring Plan	Sep. 30, 2012 Merger Restructuring Plan	Sep. 30, 2012 Merger Restructuring Plan position	Sep. 30, 2012 Merger Restructuring Plan	Dec. 31, 2011 Merger Restructuring Plan	Sep. 30, 2012 Nalco Restructuring Plan	Dec. 31, 2011 Nalco Restructuring Plan	Sep. 30, 2012 Employee termination costs 2011 Restructuring Plan	Dec. 31, 2011 Employee termination costs 2011 Restructuring Plan	Sep. 30, 2012 Employee termination costs Merger Restructuring Plan	Dec. 31, 2011 Employee termination costs Merger Restructuring Plan	Dec. 31, 2011 Asset disposals 2011 Restructuring Plan	Sep. 30, 2012 Asset disposals Merger Restructuring Plan	Sep. 30, 2012 Other 2011 Restructuring Plan	Dec. 31, 2011 Other 2011 Restructuring Plan	Sep. 30, 2012 Other Merger Restructuring Plan
Restructuring reserve
Restructuring expense and accrual					$ 82.7	$ 74.7	$ 10.6	$ 17.1	$ 42.8	$ 58.1	$ 68.1	$ 110.9	$ 12.0	$ 39.9	$ 46.5	$ 6.6			$ 41.3	$ 60.5	$ 35.4	$ 6.6	$ 0.5	$ 1.8	$ 1.5	$ 7.1	$ 2.7
Cash payments					(43.3)	(25.1)			(26.7)		(24.8)			(16.6)		(0.3)	(6.0)		(21.5)	(22.2)	(15.0)	(0.3)			(5.2)	(2.6)	(1.6)
Non-cash charges					(2.4)	(0.5)			(0.8)		(0.5)			(1.6)									(0.5)	(1.6)	(0.8)
Effect of foreign currency translation					(2.4)	(2.2)			(2.4)		(2.2)								(2.4)	(2.2)
Restructuring liability	86.2	57.5			81.5	46.9	53.5		53.5		40.6	53.5	28.0	28.0	28.0	6.3	4.7	10.6	53.5	36.1	26.7	6.3		0.2		4.5	1.1
Other restructuring information
Number of positions expected to be eliminated									750					600
Number of positions expected to be eliminated														1,500
Restructuring charge expected to be incurred through 2013, pretax									150					180
Restructuring charge expected to be incurred through 2013, after tax									125					120
Restructuring charge expected to occur in 2012, pretax									70					75
Restructuring charge expected to occur in 2012, after tax									55					55
Restructuring charges, expected cash expenditures									140					160
Restructuring charges, expected asset disposals									10					20
Restructuring charges, after tax							6.2	14.8	31.4	49.0		85.6	8.6	28.6	32.7
Non-restructuring special (gains) and charges
Nalco business combination and integration related costs, pre tax			17.9	133.4
Nalco business combination and integration related costs, net of tax			$ 11.8	$ 98.3