Cash and Cash Equivalents, Investments and Funds Held for Customers Type of issue (Details) (USD $) In Millions, unless otherwise specified																	3 Months Ended
	Oct. 31, 2012	Jul. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Oct. 31, 2012 Total cash and cash equivalents	Jul. 31, 2012 Total cash and cash equivalents	Oct. 31, 2012 Available-for-sale debt securities [Member]	Jul. 31, 2012 Available-for-sale debt securities [Member]	Oct. 31, 2012 Municipal bonds [Member]	Jul. 31, 2012 Municipal bonds [Member]	Oct. 31, 2012 Municipal auction rate securities [Member]	Jul. 31, 2012 Municipal auction rate securities [Member]	Oct. 31, 2012 Corporate notes [Member]	Jul. 31, 2012 Corporate notes [Member]	Oct. 31, 2012 U.S. agency securities [Member]	Jul. 31, 2012 U.S. agency securities [Member]	Oct. 31, 2012 Available-for-sale equity securities [Member]	Jul. 31, 2012 Available-for-sale equity securities [Member]	Oct. 31, 2012 Other long-term investments [Member]	Jul. 31, 2012 Other long-term investments [Member]
Cash and Cash Equivalents Items [Line Items]
Cash and Cash Equivalents, at Carrying Value	$ 216	$ 393	$ 333	$ 722	$ 250	$ 508
Available-for-sale Securities [Abstract]
Available-for-sale Securities, Amortized Cost Basis	549	565					549	565	252	259	33	41	145	141	119	124
Available-for-sale Equity Securities, Amortized Cost Basis																	5	5
Available-for-sale Securities, Amortized Cost Basis																			4	1
Available-for-sale Securities, Fair Value Disclosure	842	1,109			250	508	550	567	253	260	33	41	145	142	119	124	38	33	4	1
Total cash and cash equivalents investments and funds held for customers	808	1,079
Available-for-sale Securities, Gross Realized Gains																	$ 33