Postretirement and Other Employee Benefits (Weighted-Average Actuarial Assumptions) (Details)	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
Net periodic benefit cost:
Expected long-term return on plan assets	3.80%	3.30%	4.30%
Rate of compensation increase	3.30%	2.70%	2.40%
Discount rate	2.10%	1.90%	2.90%
Projected benefit obligation:
Expected long-term return on plan assets	3.60%	4.00%	3.30%
Rate of compensation increase	4.40%	4.40%	4.10%
Discount rate	2.20%	2.30%	1.70%