Cash and Cash Equivalents, Investments and Funds Held for Customers (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	$ 2,233	$ 2,233	$ 1,951
Available-for-sale securities, fair value disclosure	2,234	2,234	1,979
Available-for-sale securities:
Total cash and cash equivalents, investments and funds held for customers	2,233	2,233	1,951
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, fair value	363	363	235
Due within two years, fair value	443	443	245
Due within three years, fair value	303	303	210
Due after three years, fair value	121	121	170
Total available-for-sale debt securities, fair value	1,230	1,230	860
Available-for-sale Securities, Gross Unrealized Gains		28
Proceeds from the sale of available-for-sale equity securities	26	26	0	0
Cash And Cash Equivalents Including Funds Held For Customers [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	994	994	1,069
Available-for-sale securities, fair value disclosure	994	994	1,069
Municipal bonds [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	700	700	489
Available-for-sale securities, fair value disclosure	701	701	489
Municipal auction rate securities [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	21	21	33
Available-for-sale securities, fair value disclosure	21	21	33
Corporate notes [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	466	466	269
Available-for-sale securities, fair value disclosure	466	466	269
U.S. agency securities [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	42	42	69
Available-for-sale securities, fair value disclosure	42	42	69
Available-for-Sale Debt Securities [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	1,229	1,229	860
Available-for-sale securities, fair value disclosure	1,230	1,230	860
Equity Securities [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	0	0	5
Available-for-sale securities, fair value disclosure	0	0	33
Other Long-term Investments [Member]
Classification on balance sheets:
Available-for-sale securities, fair value disclosure	10	10	17
Available-for-sale securities:
Other long-term investments	10	10	17
Cash and Cash Equivalents [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	849	849	1,009
Available-for-sale securities, fair value disclosure	849	849	1,009
Short-term Investments [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	1,064	1,064	653
Available-for-sale securities, fair value disclosure	1,065	1,065	652
Funds Held For Customers [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	289	289	235
Available-for-sale securities, fair value disclosure	289	289	235
Long-Term Investment [Member]
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	31	31	54
Available-for-sale securities, fair value disclosure	31	31	83
Cost [Member]
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, amortized cost	363	363	234
Due within two years, amortized cost	443	443	245
Due within three years, amortized cost	303	303	211
Due after three years, amortized cost	120	120	170
Total available-for-sale debt securities, amortized cost	1,229	1,229	860
Interest and Other Income [Member]
Available-for-sale debt securities classified by the stated maturity date of the security
Available-for-sale Securities, Gross Realized Gain (Loss)	$ 21