Annual report pursuant to Section 13 and 15(d)

Leases (Details)

v3.20.4
Leases (Details) - USD ($)
$ in Thousands
12 Months Ended
Jan. 01, 2019
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Lessee, Lease, Description [Line Items]        
Operating Lease, Payments   $ 943 $ 659  
Operating Lease, Cost   979 773  
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability   388 3,325  
Lease, Cost   25,924 27,383  
Short-term Lease, Cost   23,721 36,202  
Variable Lease, Cost   21,932 23,762  
Amounts charged as dilling costs   (20,708) (33,354)  
Operating Lease, Liability, Current   $ 936 $ 847  
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]   us-gaap:OtherLiabilitiesNoncurrent us-gaap:OtherLiabilitiesNoncurrent  
Operating Lease, Liability, Noncurrent   $ 1,752 $ 2,232  
Operating Lease, Weighted Average Remaining Lease Term   3 years 1 month 6 days 4 years 1 month 6 days  
Operating Lease, Weighted Average Discount Rate, Percent   3.24% 5.97%  
Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months   $ 936    
Lessee, Operating Lease, Liability, Payments, Due Year Two   874    
Lessee, Operating Lease, Liability, Payments, Due Year Three   872    
Lessee, Operating Lease, Liability, Payments, Due Year Four   146    
Lessee, Operating Lease, Liability, Payments, Due   2,828    
Lessee, Operating Lease, Liability, Undiscounted Excess Amount   $ (140)    
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]   us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent  
Operating Lease, Liability   $ 2,688 $ 3,079  
Operating Leases, Rent Expense, Net       $ 2,700
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability, During the Year     800  
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]   us-gaap:OtherAssetsNoncurrent    
Other Noncurrent Assets        
Lessee, Lease, Description [Line Items]        
Operating Lease, Right-of-Use Asset   $ 2,432 2,740  
Accounting Standards Update 2019-01 [Member]        
Lessee, Lease, Description [Line Items]        
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability $ 2,500      
Natural Gas, Gathering, Transportation, Marketing and Processing [Member]        
Lessee, Lease, Description [Line Items]        
Lease, Cost   12,100 11,200  
Operating Expense [Member]        
Lessee, Lease, Description [Line Items]        
Lease, Cost   13,800 14,500  
General and Administrative Expense        
Lessee, Lease, Description [Line Items]        
Lease, Cost   $ 1,000 $ 800