Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Maximum percent of salary bonus and commission eligible for executive deferred compensation plan	75.00%
Executive deferred compensation plan liabilities	$ 69	$ 63
Maximum percent of pre tax salary eligible for contribution to employee plan	50.00%
Additional employer contribution for next six percent of salary in percent	125.00%
Additional salary contributed by the employee, in percent	6.00%
Matching contributions	$ 46	$ 44	$ 43