Income Taxes - Sources of income from continuing operations (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2019
Income Tax Disclosure [Abstract]
United States	$ 2,497	$ 2,206	$ 1,826
Foreign	59	(8)	55
Total	$ 2,556	$ 2,198	$ 1,881