Condensed Consolidated Balance Sheets Parenthetical (USD $) In Millions, except Share data	Jul. 31, 2011	Jul. 31, 2010
Allowance for doubtful accounts	$ 22	$ 20
Preferred stock par value	$ 0.01
Preferred stock authorized shares total	1,345,000
Preferred stock, shares issued	0
Preferred stock, shares outstanding	0
Common stock par value	$ 0.01
Common stock, shares authorized	750,000,000
Common stock, shares, outstanding	300,597,000	313,861,000
Series A Preferred Stock [Member]
Preferred stock authorized shares total	145,000
Series B Preferred Stock [Member]
Preferred stock authorized shares total	250,000