Valuation and Qualifying Accounts [Schedule] (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Allowance for Doubtful Accounts, Current [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	$ 46	$ 20	$ 22
Valuation allowances and reserves, additions charged to expense/revenue	33	34	18
Valuation allowances and reserves, deductions	(41)	(8)	(20)
Valuation allowances and reserves, ending balance	38	46	20
Allowance for Product Returns [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	19	20	20
Valuation allowances and reserves, additions charged to expense/revenue	100	92	94
Valuation allowances and reserves, deductions	(99)	(93)	(94)
Valuation allowances and reserves, ending balance	20	19	20
Reserve For Rebates [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	17	11	11
Valuation allowances and reserves, additions charged to expense/revenue	112	104	90
Valuation allowances and reserves, deductions	(114)	(98)	(90)
Valuation allowances and reserves, ending balance	$ 15	$ 17	$ 11