Description of Business and Summary of Significant Accounting Policies - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Accounting Policies [Abstract]
Net income	$ 240	$ 189	$ 297	$ 223
Shares used in basic per share amounts:
Weighted average common shares outstanding (in shares)	261	260	261	260
Shares used in diluted per share amounts:
Weighted average common shares outstanding (in shares)	261	260	261	260
Dilutive common equivalent shares from stock options and restricted stock awards (in shares)	3	4	3	4
Dilutive weighted average common shares outstanding (in shares)	264	264	264	264
Basic and diluted net income per share:
Basic net income per share (in dollars per share)	$ 0.92	$ 0.73	$ 1.14	$ 0.86
Diluted net income per share (in dollars per share)	$ 0.91	$ 0.72	$ 1.13	$ 0.84
Shares excluded from diluted net income per share:
Weighted average stock options and restricted stock units that have been excluded from dilutive common equivalent shares outstanding due to their anti-dilutive effect (in shares)	0	1	0	1