XML 48 R36.htm IDEA: XBRL DOCUMENT v3.10.0.1
Financial Instruments - Effect of Derivative Instruments on Consolidated Balance Sheets (Detail) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Derivatives, Fair Value [Line Items]    
Derivative assets $ 92 $ 388
Derivative liabilities (9,083) (3,422)
Total derivative instruments (8,991) (3,034)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Commodity Contracts [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 61  
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Commodity Contracts [Member] | Other Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 18 44
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Commodity Contracts [Member] | Derivative Liability Short-Term [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liabilities (24) (4)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Commodity Contracts [Member] | Derivative liability Long Term [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liabilities (3) (4)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Liquid Contracts [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 7  
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Liquid Contracts [Member] | Other Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets 6  
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Liquid Contracts [Member] | Derivative Liability Short-Term [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liabilities (189)  
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Crude Oil Commodity Contracts [Member] | Other Current Assets [Member]    
Derivatives, Fair Value [Line Items]    
Derivative assets   344
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Crude Oil Commodity Contracts [Member] | Derivative Liability Short-Term [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liabilities (5,503) (1,504)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Crude Oil Commodity Contracts [Member] | Derivative liability Long Term [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liabilities (3,343) $ (1,910)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Liquids [Member] | Derivative liability Long Term [Member]    
Derivatives, Fair Value [Line Items]    
Derivative liabilities $ (21)