Postretirement and Other Employee Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2021	May 31, 2020
Retirement Benefits [Abstract]
Service cost	$ 6,278	$ 6,701	$ 18,809	$ 17,802
Interest cost	1,172	755	3,469	2,327
Expected long-term return on plan assets	(3,897)	(3,741)	(11,746)	(10,316)
Recognized actuarial (gain) loss	(1,230)	225	(3,743)	674
Amortization of actuarial gains	(1,715)	0	(5,205)	0
Amortization of prior service credit	(13)	(11)	(39)	(33)
Net periodic benefit cost	$ 595	$ 3,929	$ 1,545	$ 10,454