Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 13	$ 24	$ (17)	$ (7)
Other comprehensive income (loss), net of income taxes:
Unrealized losses on available-for-sale debt securities	0	0	(1)	0
Foreign currency translation gains (losses)	3	(10)	(1)	(12)
Total other comprehensive income (loss), net	3	(10)	(2)	(12)
Comprehensive income (loss)	$ 16	$ 14	$ (19)	$ (19)