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
Beginning Balance, shares at Jul. 31, 2015		277,706
Beginning Balance at Jul. 31, 2015	$ 2,332		$ 4,010	$ (7,675)	$ (30)	$ 6,027
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive loss	(33)				(2)	(31)
Issuance of stock under employee stock plans, net of shares withheld for employee taxes, shares		998
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	$ 24		24
Stock repurchases under stock repurchase programs, shares	(14,400)	(14,359)
Stock repurchases under stock repurchase programs	$ (1,270)			(1,270)
Dividends and dividend rights declared	(82)					(82)
Tax benefit from share-based compensation plans	9		9
Share-based compensation expense	71		71
Ending Balance, shares at Oct. 31, 2015		264,345
Ending Balance at Oct. 31, 2015	1,051		4,114	(8,945)	(32)	5,914
Beginning Balance, 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, shares		975
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	$ (2)		(2)
Stock repurchases under stock repurchase programs, shares	(1,800)	(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, shares at Oct. 31, 2016		257,068
Ending Balance at Oct. 31, 2016	936		4,540	$ (10,131)	$ (37)	6,564
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle	$ 2		$ 6			$ (4)