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	943				(4)	947
Issuance of stock under employee stock plans, net of shares withheld for employee taxes (in shares)		2,642
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	89		89
Stock repurchases under stock repurchase programs (in shares)		(4,241)
Stock repurchases under stock repurchase programs	(478)			(478)
Dividends and dividend rights declared	(267)					(267)
Share-based compensation expense	247		247
Ending Balance (in shares) at Apr. 30, 2017		256,254
Ending Balance at Apr. 30, 2017	1,697		4,787	(10,417)	(36)	7,363
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	1,154				(8)	1,162
Issuance of stock under employee stock plans, net of shares withheld for employee taxes (in shares)		2,776
Issuance of stock under employee stock plans, net of shares withheld for employee taxes	$ 147		147
Stock repurchases under stock repurchase programs (in shares)	(1,900)	(1,870)
Stock repurchases under stock repurchase programs	$ (272)			(272)
Dividends and dividend rights declared	(304)					(304)
Share-based compensation expense	285		285
Ending Balance (in shares) at Apr. 30, 2018		256,574
Ending Balance at Apr. 30, 2018	$ 2,364		$ 5,289	$ (11,050)	$ (30)	$ 8,155