Fair Value Measurements - Balance Sheet Classification (Details) - USD ($) $ in Millions	Oct. 31, 2021	Jul. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	$ 2,864	$ 2,562
Available-for-sale debt securities:	584	1,508
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	696	1,660
Available-for-sale debt securities:	584	1,508
Fair value, measurements, recurring | In cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	696	1,660
Fair value, measurements, recurring | Available for sale debt securities in investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	386	1,308
Fair value, measurements, recurring | Available for sale debt securities in funds held for customers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	198	200
Fair value, measurements, recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	696	1,660
Available-for-sale debt securities:	0	0
Fair value, measurements, recurring | Level 1 | In cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	696	1,660
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]
Available-for-sale debt 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]
Available-for-sale debt securities:	0	0
Fair value, measurements, recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents:	0	0
Available-for-sale debt securities:	584	1,508
Fair value, measurements, recurring | Level 2 | In cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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]
Available-for-sale debt securities:	386	1,308
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]
Available-for-sale debt securities:	$ 198	$ 200