Annual report pursuant to Section 13 and 15(d)

Commitments (Details)

v3.22.0.1
Commitments (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Expense Relating To Surety Bonds Paid $ 6,000 $ 5,400 $ 4,700
Drilling Commitments [Member]      
Other Commitment, Fiscal Year Maturity [Abstract]      
2022 2,900    
Surety Bonds [Member]      
Other Commitment, Fiscal Year Maturity [Abstract]      
2022 7,300    
2023 6,100    
2024 6,100    
2025 6,000    
2026 5,100    
Thereafter 50,900    
Total 81,500    
Surety Bonds [Member] | Other Commitment [Member]      
Bonding Requirement, Related To Purchase of Properties Minimum Amount 64,000    
Bonding Requirement Related To Purchase of Properties Maximum Amount 94,000    
Surety Bonds [Member] | Total E&P [Member]      
Bonding Requirement Related to Purchase of Properties Amount Current Year. 96,700    
Escrow Deposit 0    
Bonding Requirement Related to Purchase of Properties Amount, Fifth Anniversary. 103,000    
Bonding Requirement Related to Purchase of Properties Amount Increment From Second Anniversary. 3,000    
Surety Bonds [Member] | Exxon [Member]      
Bonding Requirement, Related To Purchase of Properties Minimum Amount 33,000    
Other Commitment, Fiscal Year Maturity [Abstract]      
2022 36,300    
2023 40,000    
2024 44,000    
2025 48,300    
2026 53,200    
Thereafter 114,000    
Surety Bonds [Member] | Exxon [Member] | Minimum [Member]      
Annual Increase In Other Commitment 5,300    
Surety Bonds [Member] | Exxon [Member] | Maximum [Member]      
Annual Increase In Other Commitment 10,400    
Surety Bonds [Member] | Conoco [Member]      
Bonding Requirement, Related To Purchase of Properties Minimum Amount 49,000    
Heidelberg Field [Member]      
Other Commitment Expense 2,100 $ 4,500 $ 4,500
Other Commitment, Fiscal Year Maturity [Abstract]      
2022 1,800    
2023 1,200    
2024 900    
2025 600    
2026 400    
Thereafter 400    
Total $ 5,300