XML 48 R37.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments - Effect of Derivative Instruments on Consolidated Statements of Operations (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income $ (2,317) $ 2,577
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Commodity Contracts [Member] | Unrealized (Loss) Gain on Derivative Instruments, Net [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income (79) 1,313
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Commodity Contracts [Member] | Realized (Loss) Gain on Derivative Instruments, Net [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income (20) (149)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Crude Oil Commodity Contracts [Member] | Unrealized (Loss) Gain on Derivative Instruments, Net [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income (1,868) 1,491
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Crude Oil Commodity Contracts [Member] | Realized (Loss) Gain on Derivative Instruments, Net [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income (478) $ (78)
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Liquid Contracts [Member] | Unrealized (Loss) Gain on Derivative Instruments, Net [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income 126  
Derivatives Not Designated as Cash-Flow Hedging Instruments [Member] | Natural Gas Liquid Contracts [Member] | Realized (Loss) Gain on Derivative Instruments, Net [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of gain/loss recognized in income $ 2