Acquisition of Norit (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Jul. 31, 2012
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Acquisition paying	$ 1,113		$ 1,100
Acquisition costs	14
Amortized period	18 years
Fair value of the assets acquired includes trade receivables	46
Non-recurring adjustments in pro forma earnings	19
Recognized pre tax gain		33
Trademarks [Member]
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Intangible assets	57
Customer Relationships [Member]
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Intangible assets	119
Amortized period	20 years
Developed Technology [Member]
Schedule Of Business Acquisitions Purchase Price Allocation [Line Items]
Intangible assets	$ 149
Amortized period	17 years