Special (Gains) and Charges (Details 2) (USD $) In Millions, unless otherwise specified			3 Months Ended		12 Months Ended	3 Months Ended		12 Months Ended	14 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended	3 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Nalco	Mar. 31, 2012 2011 Restructuring Plan and Merger Restructuring Plan	Dec. 31, 2011 2011 Restructuring Plan and Merger Restructuring Plan	Mar. 31, 2012 2011 Restructuring Plan position	Mar. 31, 2011 2011 Restructuring Plan	Dec. 31, 2011 2011 Restructuring Plan	Mar. 31, 2012 2011 Restructuring Plan	Mar. 31, 2012 Merger Restructuring Plan position	Mar. 31, 2012 Merger Restructuring Plan	Dec. 31, 2011 Merger Restructuring Plan	Mar. 31, 2012 Nalco Restructuring Plan	Dec. 31, 2011 Nalco Restructuring Plan	Mar. 31, 2012 EMPLOYEE TERMINATION COSTS 2011 Restructuring Plan	Dec. 31, 2011 EMPLOYEE TERMINATION COSTS 2011 Restructuring Plan	Mar. 31, 2012 EMPLOYEE TERMINATION COSTS Merger Restructuring Plan	Dec. 31, 2011 EMPLOYEE TERMINATION COSTS Merger Restructuring Plan	Dec. 31, 2011 ASSET DISPOSALS 2011 Restructuring Plan	Mar. 31, 2012 OTHER 2011 Restructuring Plan	Dec. 31, 2011 OTHER 2011 Restructuring Plan	Mar. 31, 2012 OTHER Merger Restructuring Plan
Restructuring reserve
Recorded expense and accrual				$ 28.5	$ 74.7	$ 15.8		$ 68.1		$ 12.7		$ 6.6			$ 15.7	$ 60.5	$ 12.4	$ 6.6	$ 0.5	$ 0.1	$ 7.1	$ 0.3
Cash payments				(10.2)	(25.1)	(8.7)		(24.8)		(1.5)		(0.3)	1.2		(7.2)	(22.2)	(1.4)	(0.3)		(1.5)	(2.6)	(0.1)
Non-cash charges					(0.5)			(0.5)											(0.5)
Currency translation				(0.1)	(2.2)	0.3		(2.2)		(0.4)					0.3	(2.2)	(0.4)
Restructuring liability	73.8	57.5		65.1	46.9	48.0		40.6	48.0	17.1	17.1	6.3	8.7	10.6	44.9	36.1	16.9	6.3		3.1	4.5	0.2
Other restructuring information
Number of positions expected to be eliminated						750				500
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				50
Restructuring charge expected to occur in 2012, after tax						55				35
Restructuring charges, expected cash expenditures						125				150
Restructuring charges, expected asset disposals						25				30
Restructuring charges						15.8	11.2		83.9	12.7	19.3
Restructuring charges, after tax						12.6	9.0		66.8	8.8	12.9
Non-restructuring special (gains) and charges
Nalco business combination and integration related costs, pre tax			102.5
Nalco business combination and integration related costs, net of tax			$ 77.7