Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions	Total	Shares of Common Stock	Common Stock and Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 2		$ 6			$ (4)
Beginning Balance, in shares at Jul. 31, 2016		257,853
Beginning Balance at Jul. 31, 2016	1,161		4,445	$ (9,939)	$ (32)	6,687
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive loss	(35)				(5)	(30)
Issuance of stock under employee stock plans, net of shares withheld for employee taxes (in shares)		975
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	(2)		(2)
Stock repurchases under stock repurchase programs (in shares)		(1,760)
Stock repurchases under stock repurchase programs	(192)			(192)
Dividends and dividend rights declared	(89)					(89)
Share-based compensation expense	91		91
Ending Balance, in shares at Oct. 31, 2016		257,068
Ending Balance at Oct. 31, 2016	936		4,540	(10,131)	(37)	6,564
Beginning Balance, in shares at Jul. 31, 2017		255,668
Beginning Balance at Jul. 31, 2017	1,354		4,857	(10,778)	(22)	7,297
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive loss	(23)				(6)	(17)
Issuance of stock under employee stock plans, net of shares withheld for employee taxes (in shares)		1,224
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	$ 44		44
Stock repurchases under stock repurchase programs (in shares)	(1,200)	(1,225)
Stock repurchases under stock repurchase programs	$ (170)			(170)
Dividends and dividend rights declared	(100)					(100)
Share-based compensation expense	98		98
Ending Balance, in shares at Oct. 31, 2017		255,667
Ending Balance at Oct. 31, 2017	$ 1,203		$ 4,999	$ (10,948)	$ (28)	$ 7,180