Goodwill and Other Intangible Assets (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)
Goodwill and Other Intangible Assets
Number of operating units | segment	10		10
Impairment of goodwill			$ 0
Changes in the carrying amount of goodwill
Beginning goodwill, net			6,717,000,000
Current year business combinations			89,500,000
Prior year business combinations			700,000
Dispositions			(400,000)
Effect of foreign currency translation			(307,600,000)
Ending goodwill, net	$ 6,499,200,000		6,499,200,000
Goodwill expected to be tax deductible	900,000		900,000
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
Total amortization expense related to other intangible assets	72,600,000	$ 75,200,000	218,600,000	$ 230,000,000
Future estimated amortization expense related to amortizable other identifiable intangible assets
2015 (Remainder: three-month period)	73,000,000		73,000,000
2016	287,000,000		287,000,000
2017	285,000,000		285,000,000
2018	279,000,000		279,000,000
2019	267,000,000		267,000,000
2020	263,000,000		263,000,000
Nalco | Trademarks
Changes in the carrying amount of goodwill
Impairment of indefinite life intangible asset			0
Indefinite-Lived Intangible Assets (Excluding Goodwill) [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	1,200,000,000		1,200,000,000
Global Industrial
Changes in the carrying amount of goodwill
Beginning goodwill, net			2,642,200,000
Current year business combinations			82,500,000
Prior year business combinations			700,000
Dispositions			(400,000)
Reclassifications			(23,700,000)
Effect of foreign currency translation			(120,500,000)
Ending goodwill, net	2,580,800,000		2,580,800,000
Global Institutional
Changes in the carrying amount of goodwill
Beginning goodwill, net			691,200,000
Current year business combinations			6,100,000
Reclassifications			2,900,000
Effect of foreign currency translation			(31,900,000)
Ending goodwill, net	668,300,000		668,300,000
Global Energy
Changes in the carrying amount of goodwill
Beginning goodwill, net			3,262,100,000
Reclassifications			20,800,000
Effect of foreign currency translation			(149,600,000)
Ending goodwill, net	3,133,300,000		$ 3,133,300,000
Other
Goodwill and Other Intangible Assets
Number of operating units | segment			2
Changes in the carrying amount of goodwill
Beginning goodwill, net			$ 121,500,000
Current year business combinations			900,000
Effect of foreign currency translation			(5,600,000)
Ending goodwill, net	$ 116,800,000		$ 116,800,000