Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 189	$ 183	$ 223	$ 181
Other comprehensive income (loss), net of income taxes:
Unrealized gain (loss) on available-for-sale debt securities	1	(1)	1	(1)
Foreign currency translation gain (loss)	3	10	(1)	3
Total other comprehensive income (loss), net	4	9	0	2
Comprehensive income	$ 193	$ 192	$ 223	$ 183