Fair Value Measurements (Details 1) (USD $) In Millions, unless otherwise specified	Apr. 30, 2015	Jul. 31, 2014
Cash and Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	$ 1,193	$ 849
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]
Cash equivalents:
Total cash equivalents	770	652
Available-for-sale securities:
Total available-for-sale securities	1,087	1,230
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Cash and Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	615	507
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Cash equivalents in funds held for customers [Member]
Cash equivalents:
Total cash equivalents	155	145
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Available For Sale Debt Securities In Investments [Member]
Available-for-sale securities:
Total available-for-sale securities	891	1,065
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Available For Sale Debt Securities In Funds Held For Customers [Member]
Available-for-sale securities:
Total available-for-sale securities	175	144
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Available For Sale Debt Securities In long term investments [Member]
Available-for-sale securities:
Total available-for-sale securities	21	21
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents:
Total cash equivalents	770	652
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	615	507
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Cash equivalents in funds held for customers [Member]
Cash equivalents:
Total cash equivalents	155	145
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Available For Sale Debt Securities In Investments [Member]
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Available For Sale Debt Securities In Funds Held For Customers [Member]
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Available For Sale Debt Securities In long term investments [Member]
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents:
Total cash equivalents	0	0
Available-for-sale securities:
Total available-for-sale securities	1,066	1,209
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Cash equivalents in funds held for customers [Member]
Cash equivalents:
Total cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Available For Sale Debt Securities In Investments [Member]
Available-for-sale securities:
Total available-for-sale securities	891	1,065
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Available For Sale Debt Securities In Funds Held For Customers [Member]
Available-for-sale securities:
Total available-for-sale securities	175	144
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Available For Sale Debt Securities In long term investments [Member]
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents:
Total cash equivalents	0	0
Available-for-sale securities:
Total available-for-sale securities	21	21
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]
Cash equivalents:
Total cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cash equivalents in funds held for customers [Member]
Cash equivalents:
Total cash equivalents	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Available For Sale Debt Securities In Investments [Member]
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Available For Sale Debt Securities In Funds Held For Customers [Member]
Available-for-sale securities:
Total available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Available For Sale Debt Securities In long term investments [Member]
Available-for-sale securities:
Total available-for-sale securities	$ 21	$ 21