Quarterly report pursuant to Section 13 or 15(d)

Crude Oil and Natural Gas Properties and Equipment (Crude Oil and Natural Gas Properties and Equipment) (Details)

v3.21.2
Crude Oil and Natural Gas Properties and Equipment (Crude Oil and Natural Gas Properties and Equipment) (Details) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Property, Plant and Equipment [Line Items]    
Gross crude oil and natural gas properties and equipment $ 519,153 $ 472,800
Accumulated depreciation, depletion, amortization and impairment (444,951) (435,764)
Net crude oil and natural gas properties, equipment and other 74,202 37,036
Wells, Platforms and Other Production Facilities [Member]    
Property, Plant and Equipment [Line Items]    
Gross crude oil and natural gas properties and equipment 477,908 441,879
Work-in-Progress [Member]    
Property, Plant and Equipment [Line Items]    
Gross crude oil and natural gas properties and equipment 1,172 169
Undeveloped Acreage [Member]    
Property, Plant and Equipment [Line Items]    
Gross crude oil and natural gas properties and equipment 23,735 21,476
Equipment and Other [Member]    
Property, Plant and Equipment [Line Items]    
Gross crude oil and natural gas properties and equipment $ 16,338 $ 9,276