Fair Value Measurements - Fair Value Reconciliation Liabilities Using Significant Unobservable Inputs (3 month) (Level 3) (Details) - National Cooperative Refinery Association [Member] - Crack Spread Contingent Payment [Member] - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2015	Nov. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance	$ 75,982	$ 114,917
Balance	43,693	86,520
Cost of Goods, Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in cost of goods sold and net interest	$ (32,289)	$ (28,397)