Description of Business and Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Numerator:
Net loss	$ (17)	$ (30)
Shares used in basic per share amounts:
Weighted average common shares outstanding (in shares)	256	258
Shares used in diluted per share amounts:
Weighted average common shares outstanding (in shares)	256	258
Dilutive common equivalent shares from stock options and restricted stock awards (in shares)	0	0
Dilutive weighted average common shares outstanding (in shares)	256	258
Basic and diluted net loss per share:
Basic net loss per share (in dollars per share)	$ (0.07)	$ (0.12)
Diluted net loss per share (in dollars per share)	$ (0.07)	$ (0.12)
Shares excluded from computation of diluted net loss per share:
Weighted average stock options and restricted stock units that would have been included in the computation of dilutive common equivalent shares outstanding if net income had been reported in the period (in shares)	12	12
Weighted average stock options and restricted stock units that would have been excluded from the computation of dilutive common equivalent shares outstanding if net income had been reported in the period due to their anti-dilutive effect (in shares)	2	4