XML 46 R35.htm IDEA: XBRL DOCUMENT v3.19.1
Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Assets    
Derivative assets $ 118 $ 2,394
Liabilities    
Derivative liabilities (3,574) (98)
Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets 118 2,394
Liabilities    
Derivative liabilities (3,574) (98)
Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets 118 2,394
Liabilities    
Derivative liabilities $ (3,574) (98)
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets   2,394
Liabilities    
Derivative liabilities   (98)
Significant Unobservable Inputs (Level 3) [Member] | Commodity Contract [Member] | Fair Value, Measurements, Recurring [Member]    
Assets    
Derivative assets   2,394
Liabilities    
Derivative liabilities   $ (98)