Fair Value Measurements (Details 2) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Jul. 31, 2015	Jul. 31, 2014
Cash equivalents:
Cash equivalents	$ 695	$ 652
Available-for-sale securities:
Investments	1,079	1,230
Cash and cash equivalents
Cash equivalents:
Cash equivalents	533	507
Cash equivalents in funds held for customers
Cash equivalents:
Cash equivalents	162	145
Available-for-sale securities in investments
Available-for-sale securities:
Investments	889	1,065
Available-for-sale securities in funds held for customers
Available-for-sale securities:
Investments	175	144
Available-for-sale securities in long-term investments
Available-for-sale securities:
Investments	15	21
Level 1
Cash equivalents:
Cash equivalents	695	652
Available-for-sale securities:
Investments	0	0
Level 1 | Cash and cash equivalents
Cash equivalents:
Cash equivalents	533	507
Level 1 | Cash equivalents in funds held for customers
Cash equivalents:
Cash equivalents	162	145
Level 1 | Available-for-sale securities in investments
Available-for-sale securities:
Investments	0	0
Level 1 | Available-for-sale securities in funds held for customers
Available-for-sale securities:
Investments	0	0
Level 1 | Available-for-sale securities in long-term investments
Available-for-sale securities:
Investments	0	0
Level 2
Cash equivalents:
Cash equivalents	0	0
Available-for-sale securities:
Investments	1,064	1,209
Level 2 | Cash and cash equivalents
Cash equivalents:
Cash equivalents	0	0
Level 2 | Cash equivalents in funds held for customers
Cash equivalents:
Cash equivalents	0	0
Level 2 | Available-for-sale securities in investments
Available-for-sale securities:
Investments	889	1,065
Level 2 | Available-for-sale securities in funds held for customers
Available-for-sale securities:
Investments	175	144
Level 2 | Available-for-sale securities in long-term investments
Available-for-sale securities:
Investments	0	0
Level 3
Cash equivalents:
Cash equivalents	0	0
Available-for-sale securities:
Investments	15	21
Level 3 | Cash and cash equivalents
Cash equivalents:
Cash equivalents	0	0
Level 3 | Cash equivalents in funds held for customers
Cash equivalents:
Cash equivalents	0	0
Level 3 | Available-for-sale securities in investments
Available-for-sale securities:
Investments	0	0
Level 3 | Available-for-sale securities in funds held for customers
Available-for-sale securities:
Investments	0	0
Level 3 | Available-for-sale securities in long-term investments
Available-for-sale securities:
Investments	$ 15	$ 21