Postretirement and Other Employee Benefits (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Postretirement and Other Employee Benefits [Abstract]
Service cost	$ 259	$ 222	$ 771	$ 662
Interest cost	744	1,208	2,222	3,693
Expected long-term return on plan assets	(1,127)	(1,383)	(3,365)	(4,243)
Recognized actuarial loss	479	264	1,422	790
Amortization of prior service credit	(34)	(35)	(101)	(104)
Net periodic benefit cost	$ 321	$ 276	$ 949	$ 798