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 change in accounting principle	$ 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 income (loss)	(19)				(2)	(17)
Issuance of stock under employee stock plans, net of shares withheld for employee taxes (in shares)		1,649
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	35		35
Stock repurchases under stock repurchase programs (in shares)		(3,500)
Stock repurchases under stock repurchase programs	(390)			(390)
Dividends and dividend rights declared	(178)					(178)
Share-based compensation expense	174		174
Ending Balance, in shares at Jan. 31, 2017		256,002
Ending Balance at Jan. 31, 2017	785		4,660	(10,329)	(34)	6,488
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 income (loss)	(36)				2	(38)
Issuance of stock under employee stock plans, net of shares withheld for employee taxes (in shares)		2,163
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	$ 101		101
Stock repurchases under stock repurchase programs (in shares)	(1,800)	(1,755)
Stock repurchases under stock repurchase programs	$ (253)			(253)
Dividends and dividend rights declared	(202)					(202)
Share-based compensation expense	193		193
Ending Balance, in shares at Jan. 31, 2018		256,076
Ending Balance at Jan. 31, 2018	$ 1,157		$ 5,151	$ (11,031)	$ (20)	$ 7,057