Fair Value Measurements (Details 2) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Jul. 31, 2016	Jul. 31, 2015
Cash equivalents:
Cash equivalents	$ 416	$ 695
Available-for-sale securities:
Investments	657	1,079
Level 1
Cash equivalents:
Cash equivalents	416	695
Available-for-sale securities:
Investments	0	0
Level 2
Cash equivalents:
Cash equivalents	0	0
Available-for-sale securities:
Investments	642	1,064
Level 3
Cash equivalents:
Cash equivalents	0	0
Available-for-sale securities:
Investments	15	15
Cash and cash equivalents
Cash equivalents:
Cash equivalents	312	533
Cash and cash equivalents | Level 1
Cash equivalents:
Cash equivalents	312	533
Cash and cash equivalents | Level 2
Cash equivalents:
Cash equivalents	0	0
Cash and cash equivalents | Level 3
Cash equivalents:
Cash equivalents	0	0
Cash equivalents in funds held for customers
Cash equivalents:
Cash equivalents	104	162
Cash equivalents in funds held for customers | Level 1
Cash equivalents:
Cash equivalents	104	162
Cash equivalents in funds held for customers | Level 2
Cash equivalents:
Cash equivalents	0	0
Cash equivalents in funds held for customers | Level 3
Cash equivalents:
Cash equivalents	0	0
Available for sale debt securities in investments
Available-for-sale securities:
Investments	442	889
Available for sale debt securities in investments | Level 1
Available-for-sale securities:
Investments	0	0
Available for sale debt securities in investments | Level 2
Available-for-sale securities:
Investments	442	889
Available for sale debt securities in investments | Level 3
Available-for-sale securities:
Investments	0	0
Available for sale debt securities in funds held for customers
Available-for-sale securities:
Investments	200	175
Available for sale debt securities in funds held for customers | Level 1
Available-for-sale securities:
Investments	0	0
Available for sale debt securities in funds held for customers | Level 2
Available-for-sale securities:
Investments	200	175
Available for sale debt securities in funds held for customers | Level 3
Available-for-sale securities:
Investments	0	0
Available for sale securities in long term investments
Available-for-sale securities:
Investments	15	15
Available for sale securities in long term investments | Level 1
Available-for-sale securities:
Investments	0	0
Available for sale securities in long term investments | Level 2
Available-for-sale securities:
Investments	0	0
Available for sale securities in long term investments | Level 3
Available-for-sale securities:
Investments	$ 15	$ 15