Benefit Plans - Schedule of Amortization from Other Accumulated Comprehensive Income into Net Period Benefit Costs (Details) $ in Thousands	Aug. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, health care benefits annual rate of increase in the per capita cost	7.50%
Defined benefit plan, health care benefits, decrease in the per capita cost trend rate	4.50%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fiscal 2018 Amortization of prior service cost (credit)	$ 190
Fiscal 2018 Amortization of net actuarial (gain) loss	12,266
Non-Qualified Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fiscal 2018 Amortization of prior service cost (credit)	(75)
Fiscal 2018 Amortization of net actuarial (gain) loss	2
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Fiscal 2018 Amortization of prior service cost (credit)	(556)
Fiscal 2018 Amortization of net actuarial (gain) loss	$ (1,629)