Pensions and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Components of net periodic benefit cost
Service cost	$ 74	$ 67	$ 221	$ 213
Interest cost	112	172	338	528
Expected return on plan assets	(98)	(104)	(294)	(325)
Amortization of prior service cost	1	1	3	3
Amortization of accumulated loss	174	112	522	349
Curtailment and settlement loss	75	11	75	484
Net periodic benefit cost	$ 338	$ 259	865	1,252
Employer contribution			$ 1,170	$ 1,177