Income Taxes Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Income Tax Disclosure [Abstract]
Beginning balance	$ 1,465	$ 1,357	$ 1,262
Additions for tax positions related to the current year	123	143	150
Additions for tax positions of prior years	84	36	20
Reductions for tax positions of prior years	(43)	(58)	(62)
Settlements with taxing authorities	(160)	0	(5)
Statute closings	(45)	(13)	(8)
Audit Resolutions	(79)	0	0
Ending balance	$ 1,345	$ 1,465	$ 1,357