Postretirement and Other Employee Benefits (Fair Value of Plan Assets) (Details) - USD ($) $ in Millions	Aug. 31, 2021	Aug. 31, 2020	Aug. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 576	$ 538	$ 158
Asset Allocation	100.00%	100.00%
Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 15	$ 15
Asset Allocation	3.00%	3.00%
Global equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 222	$ 208
Asset Allocation	39.00%	38.00%
Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 262	$ 238
Asset Allocation	45.00%	44.00%
Government bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 58	$ 58
Asset Allocation	10.00%	11.00%
Insurance contracts | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair Value	$ 19	$ 19
Asset Allocation	3.00%	4.00%