Fair Value Measurements - Fair Value Reconciliation Liabilities Using Significant Unobservable Inputs (Level 3) (Details) - NCRA [Member] - Crack Spread Contingent Payment [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2017	Feb. 29, 2016	Feb. 28, 2017	Feb. 29, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 8,281	$ 43,693	$ 15,051	$ 75,982
Ending Balance	2,172	24,155	2,172	24,155
Cost of Goods, Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total (gains) losses included in cost of goods sold	$ (6,109)	$ (19,538)	$ (12,879)	$ (51,827)