Benefit Plans - Schedule of Amortization From Other Accumulated Comprehensive Income into Net Period Benefit Costs (Details) $ in Thousands	12 Months Ended
	Aug. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, health care benefits annual rate of increase in the per capita cost	7.60%
Defined benefit plan, health care benefits, decrease in the per capita cost trend rate	4.50%
Qualified Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fiscal 2017 Amortization of prior service cost (benefit)	$ 1,563
Fiscal 2017 Amortization of net actuarial (gain) loss	26,969
Non-Qualified Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fiscal 2017 Amortization of prior service cost (benefit)	19
Fiscal 2017 Amortization of net actuarial (gain) loss	546
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Fiscal 2017 Amortization of prior service cost (benefit)	(565)
Fiscal 2017 Amortization of net actuarial (gain) loss	$ (913)