Pension and Postretirement Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended		1 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012 U.S. PENSION	Sep. 30, 2011 U.S. PENSION	Jun. 30, 2011 U.S. PENSION	Sep. 30, 2012 U.S. PENSION	Sep. 30, 2011 U.S. PENSION	Apr. 30, 2012 U.S. PENSION Nalco	Sep. 30, 2012 U.S. PENSION Nalco	Sep. 30, 2012 INTERNATIONAL PENSION	Sep. 30, 2011 INTERNATIONAL PENSION	Sep. 30, 2012 INTERNATIONAL PENSION	Sep. 30, 2011 INTERNATIONAL PENSION	Sep. 30, 2012 U.S. POSTRETIREMENT HEALTH CARE	Sep. 30, 2011 U.S. POSTRETIREMENT HEALTH CARE	Sep. 30, 2012 U.S. POSTRETIREMENT HEALTH CARE	Sep. 30, 2011 U.S. POSTRETIREMENT HEALTH CARE	Sep. 30, 2012 U.S. non-contributory non-qualified defined benefit plans
Net periodic benefit costs
Service cost	$ 12.6	$ 11.7		$ 37.8	$ 35.1			$ 7.1	$ 6.0	$ 21.8	$ 17.5	$ 1.3	$ 0.5	$ 3.9	$ 1.5
Interest cost on benefit obligation	22.3	15.3		66.9	45.9			11.6	7.2	35.4	21.2	3.2	2.1	9.6	6.3
Expected return on plan assets	(31.8)	(24.7)		(95.4)	(74.1)			(10.4)	(5.7)	(31.6)	(16.9)	(0.3)	(0.4)	(0.9)	(1.2)
Recognition of net actuarial loss	11.3	8.0		33.9	24.0			0.9	1.5	2.9	4.3	0.1	0.1	0.3	0.3
Amortization of prior service benefit	(1.0)	(1.1)		(3.0)	(3.3)			(0.1)		(0.2)
Settlements/Curtailments										0.8
Total expense	13.4	9.2		40.2	27.6			9.1	9.0	29.1	26.1	4.3	2.3	12.9	6.9
Other Pension Plan Information
Required contributions to defined benefit plan in current fiscal year							38
Payments to plan							30			33				11		8
Contributions expected to be made during the remainder of the current fiscal year								11		11		4		4		3
Employer voluntary contribution to defined benefit plan			$ 100			$ 150