Stockholders' Equity - Restricted Stock Unit Activity and Related Share-Based Compensation Expense (Details) - Restricted Stock Units (RSUs) $ / shares in Units, shares in Thousands, $ in Millions	9 Months Ended
	Apr. 30, 2020 USD ($) $ / shares shares
Number of Shares
Nonvested at beginning of period (in shares) | shares	5,683
Granted (in shares) | shares	660
Vested (in shares) | shares	(1,000)
Forfeited (in shares) | shares	(590)
Nonvested at end of period (in shares) | shares	4,753
Weighted Average Grant Date Fair Value
Nonvested, weighted average grant date fair value, at beginning of period (in dollars per shares) | $ / shares	$ 186.22
Granted, weighted average grant date fair value (in dollars per shares) | $ / shares	262.61
Vested, weighted average grant date fair value (in dollars per shares) | $ / shares	165.90
Forfeited, weighted average grant date fair value (in dollars per shares) | $ / shares	149.44
Nonvested, weighted average grant date fair value, at end of period (in dollars per shares) | $ / shares	$ 205.65
Unrecognized compensation cost related to non-vested RSUs | $	$ 754
Weighted average vesting period, in years	2 years 9 months 18 days