Stockholders' Equity - Stock-Option Activity and Related Share-Based Compensation Expense (Details) $ / shares in Units, shares in Thousands, $ in Millions	9 Months Ended
	Apr. 30, 2018 USD ($) $ / shares shares
Number of Shares
Options outstanding, beginning balance (in shares) | shares	7,488
Options granted, number of shares (in shares) | shares	0
Options exercised, number of shares (in shares) | shares	(1,717)
Options canceled or expired, number of shares (in shares) | shares	(320)
Options outstanding, ending balance (in shares) | shares	5,451
Weighted Average Exercise Price Per Share
Weighted average exercise price per share, Beginning Balance (in dollars per share) | $ / shares	$ 104.50
Options granted, weighted average exercise price per share (in dollars per share) | $ / shares	0
Options exercised, weighted average exercise price per share (in dollars per share) | $ / shares	86.16
Options canceled or expired, weighted average exercise price per share (in dollars per share) | $ / shares	120.28
Weighted average exercise price per share, Ending Balance (in dollars per share) | $ / shares	$ 109.35
Exercisable (in shares) | shares	2,825
Exercisable, Weighted average exercise price per share (in dollars per share) | $ / shares	$ 93.12
Employee Stock Option
Weighted Average Exercise Price Per Share
Unrecognized compensation cost related to non-vested share based compensation expense | $	$ 50
Expected weighted average vesting period to recognize compensation cost related to share based compensation expense, in years	1 year 9 months 18 days