Cash and Cash Equivalents, Investments and Funds Held for Customers (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2013	Jul. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities, Gross Unrealized Gains	$ 28
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	1,979	1,109
Available-for-sale securities, amortized cost basis	1,951	1,079
Total cash and cash equivalents, investments and funds held for customers	1,951	1,079
Available-for-sale securities:
Total cash and cash equivalents, investments and funds held for customers	1,951	1,079
Cash And Cash Equivalents Including Funds Held For Customers [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	1,069	508
Available-for-sale securities, amortized cost basis	1,069	508
Municipal bonds [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	489	260
Available-for-sale securities, amortized cost basis	489	259
Municipal auction rate securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	33	41
Available-for-sale securities, amortized cost basis	33	41
Corporate notes [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	269	142
Available-for-sale securities, amortized cost basis	269	141
U.S. agency securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	69	124
Available-for-sale securities, amortized cost basis	69	124
Available-for-Sale Debt Securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	860	567
Available-for-sale securities, amortized cost basis	860	565
Equity Securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	33	33
Available-for-sale securities, amortized cost basis	5	5
Other Long-term Investments [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	17	1
Available-for-sale securities:
Other long-term investments	17	1
Cost [Member]
Available-for-sale securities:
Total available-for-sale debt securities, amortized cost	860	565
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, amortized cost	234	218
Due within two years, amortized cost	245	134
Due within three years, amortized cost	211	131
Due after three years, amortized cost	170	82
Total available-for-sale debt securities, amortized cost	860	565
Fair Value [Member]
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, fair value	235	218
Due within two years, fair value	245	135
Due within three years, fair value	210	132
Due after three years, fair value	170	82
Total available-for-sale debt securities, fair value	860	567
Cash and Cash Equivalents [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	1,009	393
Available-for-sale securities, amortized cost basis	1,009	393
Short-term Investments [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	652	351
Available-for-sale securities, amortized cost basis	653	350
Funds Held For Customers [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	235	290
Available-for-sale securities, amortized cost basis	235	289
Long-Term Investment [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	83	75
Available-for-sale securities, amortized cost basis	$ 54	$ 47