Description of Business and Summary of Significant Accounting Policies - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Accounting Policies [Abstract]
Net income	$ 198	$ 57
Shares used in basic per share amounts:
Weighted average common shares outstanding (in shares)	263,000,000	261,000,000
Shares used in diluted per share amounts:
Weighted average common shares outstanding (in shares)	263,000,000	261,000,000
Dilutive common equivalent shares from stock options and restricted stock awards (in shares)	2,000,000	3,000,000
Dilutive weighted average common shares outstanding (in shares)	265,000,000	264,000,000
Basic and diluted net income per share:
Basic net income per share (in dollars per share)	$ 0.75	$ 0.22
Diluted net income per share (in dollars per share)	$ 0.75	$ 0.22
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)	1,000,000	0