Cash, Cash Equivalents and Investments (Details 1) (USD $) In Millions	Jul. 31, 2011
Contractual maturities of investments
Due in one year or less, Cost	$ 704
Due in one year or less, Estimated Fair value	707
Due after one through five years, Cost	618
Due after one through five years, Estimated Fair Value	626
Due after five years, Cost	3
Due after five years, Estimated Fair Value	3
No single maturity date, Cost	432
No single maturity date, Estimated Fair Value	455
Investments maturities amortized cost	1,757
Investments maturities fair value	$ 1,791