Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 240	$ 189	$ 297	$ 223
Other comprehensive income (loss), net of income taxes:
Unrealized gain on available-for-sale debt securities	1	1	2	1
Foreign currency translation gain (loss)	(1)	3	(1)	(1)
Total other comprehensive income, net	0	4	1	0
Comprehensive income	$ 240	$ 193	$ 298	$ 223