Cash and Cash Equivalents, Investments and Funds Held for Customers (Details) - USD ($) $ in Millions	Jul. 31, 2016	Jul. 31, 2015
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	$ 1,411	$ 2,062
Available-for-sale securities, fair value disclosure	1,412	2,061
Total cash and cash equivalents investments and funds held for customers	1,411	2,062
Available-for-sale debt securities classified by the stated maturity date of the security
Due within one year, amortized cost	285	434
Due within one year, fair value	285	435
Due within two years, amortized cost	209	443
Due within two years, fair value	210	442
Due within three years, amortized cost	143	156
Due within three years, fair value	143	156
Due after three years, amortized cost	19	47
Due after three years, fair value	19	46
Total available-for-sale debt securities, amortized cost	656	1,080
Total available-for-sale debt securities, fair value	657	1,079
Cash and cash equivalents including funds held for customers
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	742	970
Available-for-sale securities, fair value disclosure	742	970
Municipal bonds
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	186	507
Available-for-sale securities, fair value disclosure	186	506
Municipal auction rate securities
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	15	15
Available-for-sale securities, fair value disclosure	15	15
Corporate notes
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	419	546
Available-for-sale securities, fair value disclosure	420	546
U.S. agency securities
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	36	12
Available-for-sale securities, fair value disclosure	36	12
Available-for-sale debt securities
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	656	1,080
Available-for-sale securities, fair value disclosure	657	1,079
Other long-term investments
Available-for-sale securities:
Other long-term investments	13	12
Cash and cash equivalents
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	638	808
Available-for-sale securities, fair value disclosure	638	808
Short-term investments
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	441	890
Available-for-sale securities, fair value disclosure	442	889
Funds held for customers
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	304	337
Available-for-sale securities, fair value disclosure	304	337
Long-term investment
Classification on balance sheets:
Available-for-sale securities, amortized cost basis	28	27
Available-for-sale securities, fair value disclosure	28	27
Fair value measurement | Other long-term investments
Available-for-sale securities:
Other long-term investments	$ 13	$ 12