Cash and Cash Equivalents, Investments and Funds Held for Customers (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2012	Jul. 31, 2011
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	1,109	1,898
Available-for-sale securities, amortized cost basis	1,079	1,896
Total cash and cash equivalents, investments and funds held for customers	1,079	1,896
Available-for-sale securities:
Total cash and cash equivalents, investments and funds held for customers	1,079	1,896
Cash And Cash Equivalents Including Funds Held For Customers [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	508	961
Available-for-sale securities, amortized cost basis	508	961
Municipal bonds [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	260	434
Available-for-sale securities, amortized cost basis	259	434
Municipal auction rate securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	41	59
Available-for-sale securities, amortized cost basis	41	59
Corporate notes [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	142	288
Available-for-sale securities, amortized cost basis	141	287
U.S. agency securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	124	152
Available-for-sale securities, amortized cost basis	124	151
Available-for-Sale Debt Securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	567	933
Available-for-sale securities, amortized cost basis	565	931
Equity Securities [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	33	0
Available-for-sale securities, amortized cost basis	5	0
Other Long-term Investments [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	1	4
Available-for-sale securities:
Other long-term investments	1	4
Cost [Member]
Available-for-sale securities:
Total available-for-sale debt securities, amortized cost	565	931
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, amortized cost	218	267
Due within two years, amortized cost	134	323
Due within three years, amortized cost	131	190
Due after three years, amortized cost	82	151
Total available-for-sale debt securities, amortized cost	565	931
Fair Value [Member]
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, fair value	218	267
Due within two years, fair value	135	324
Due within three years, fair value	132	191
Due after three years, fair value	82	151
Total available-for-sale debt securities, fair value	567	933
Cash and Cash Equivalents [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	393	722
Available-for-sale securities, amortized cost basis	393	722
Short-term Investments [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	351	699
Available-for-sale securities, amortized cost basis	350	698
Funds Held For Customers [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	290	414
Available-for-sale securities, amortized cost basis	289	413
Long-Term Investment [Member]
Classification on balance sheets:
Available-for-sale securites, fair value discolusre	75	63
Available-for-sale securities, amortized cost basis	$ 47	$ 63