Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 1,211	$ 971	$ 979
Other comprehensive income (loss), net of income taxes:
Unrealized gain (loss) on available-for-sale debt securities	(2)	(1)	1
Foreign currency translation gain (loss)	(11)	11	(3)
Total other comprehensive income (loss), net	(13)	10	(2)
Comprehensive income	$ 1,198	$ 981	$ 977