XML 64 R50.htm IDEA: XBRL DOCUMENT v3.8.0.1
Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - Derivatives Not Designated as Hedging Instruments under FASB ASC 815-10 - Commodity Contract - USD ($)
$ in Thousands
Sep. 30, 2017
Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts $ 8,725 $ 13,061
Derivative Liabilities, commodity contracts (2,817) (10,555)
Fair asset and fair liability value of derivative instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts 7,729 11,692
Other long-term liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts   1,369
Derivative Liabilities, commodity contracts   (565)
Fair liability and fair asset value of derivative instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts (2,086) (9,990)
Cash Collateral    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts 0 0
Other long-term assets, net    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts 996  
Deferred charges and other assets, net and other long-term liabilities balances    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts (731)  
Quoted Prices in Active Markets for Identical Assets Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts   481
Derivative Liabilities, commodity contracts   (2,087)
Quoted Prices in Active Markets for Identical Assets Level 1 | Other long-term liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts   481
Derivative Liabilities, commodity contracts   (484)
Quoted Prices in Active Markets for Identical Assets Level 1 | Fair liability and fair asset value of derivative instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts   (1,603)
Quoted Prices in Active Markets for Identical Assets Level 1 | Cash Collateral    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts 0 0
Significant Other Observable Inputs Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts 8,725 12,580
Derivative Liabilities, commodity contracts (2,817) (8,468)
Significant Other Observable Inputs Level 2 | Fair asset and fair liability value of derivative instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts 7,729 11,692
Significant Other Observable Inputs Level 2 | Other long-term liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts   888
Derivative Liabilities, commodity contracts   (81)
Significant Other Observable Inputs Level 2 | Fair liability and fair asset value of derivative instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts (2,086) (8,387)
Significant Other Observable Inputs Level 2 | Cash Collateral    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts 0 $ 0
Significant Other Observable Inputs Level 2 | Other long-term assets, net    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Assets, commodity contracts 996  
Significant Other Observable Inputs Level 2 | Deferred charges and other assets, net and other long-term liabilities balances    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative Liabilities, commodity contracts $ (731)