Acquisition of Norit (Pro Forma Net Sales and Results of Operations) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Mar. 31, 2012	Mar. 31, 2012
Business Combinations [Abstract]
Net sales	$ 928	$ 1,774
Income from continuing operations	$ 55	$ 91
Income from continuing operations per common share:
Basic	$ 0.86	$ 1.42
Diluted	$ 0.85	$ 1.41