Investments in Affiliates (Schedule of Summarized Income Statement Information for Ibn Sina (National Methanol)) (Details) (National Methonal Company (Ibn Sina) [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
National Methonal Company (Ibn Sina) [Member]
Revenues	$ 1,204	$ 923	$ 630
Gross profit	546	403	256
Net income	$ 481	$ 357	$ 222