Fair Value Measurements Balance Sheet Classification (Details ) - USD ($) $ in Millions	Apr. 30, 2017	Jul. 31, 2016
Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	$ 1,350	$ 638
Fair value, measurements, recurring | Estimate of fair value measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	630	416
Total available-for-sale securities	458	657
Fair value, measurements, recurring | Cash and cash equivalents | Estimate of fair value measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	630	312
Fair value, measurements, recurring | Cash equivalents in funds held for customers | Estimate of fair value measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	104
Fair value, measurements, recurring | Available for sale debt securities in investments | Estimate of fair value measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	243	442
Fair value, measurements, recurring | Available for sale debt securities in funds held for customers | Estimate of fair value measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	200	200
Fair value, measurements, recurring | Available for sale debt securities in long term investments | Estimate of fair value measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	15	15
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	630	416
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	630	312
Fair value, measurements, recurring | Level 1 | Cash equivalents in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	104
Fair value, measurements, recurring | Level 1 | Available for sale debt securities in investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 1 | Available for sale debt securities in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 1 | Available for sale debt securities in long term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Total available-for-sale securities	443	642
Fair value, measurements, recurring | Level 2 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Fair value, measurements, recurring | Level 2 | Cash equivalents in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Fair value, measurements, recurring | Level 2 | Available for sale debt securities in investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	243	442
Fair value, measurements, recurring | Level 2 | Available for sale debt securities in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	200	200
Fair value, measurements, recurring | Level 2 | Available for sale debt securities in long term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Total available-for-sale securities	15	15
Fair value, measurements, recurring | Level 3 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Fair value, measurements, recurring | Level 3 | Cash equivalents in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash equivalents	0	0
Fair value, measurements, recurring | Level 3 | Available for sale debt securities in investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 3 | Available for sale debt securities in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	0	0
Fair value, measurements, recurring | Level 3 | Available for sale debt securities in long term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total available-for-sale securities	$ 15	$ 15