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Fair Value Measurements - Quantitative Information about Level 3 Fair Value Measurements (Details) - NCRA [Member] - USD ($)
3 Months Ended
Nov. 30, 2016
Aug. 31, 2016
Nov. 30, 2015
Aug. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items]        
Crack spread contingent consideration liability $ 8,281,000      
Crack Spread Contingent Payment [Member]        
Fair Value Inputs, Assets, Quantitative Information [Line Items]        
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value 8,281,000 $ 15,051,000 $ 46,693,000 $ 78,982,000
Crack Spread Contingent Payment [Member] | Fair Value, Inputs, Level 3 [Member]        
Fair Value Inputs, Assets, Quantitative Information [Line Items]        
Forward crack spread margin $ 9.32      
Contractual target crack spread margin (in dollars per share) $ 17.50      
Expected volatility 143.31%      
Own credit risk 0.94%      
Expected life (years) 9 months