Annual report pursuant to Section 13 and 15(d)

Note 20 - Supplemental Oil and Gas Disclosures - Unaudited (Details Textual)

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Note 20 - Supplemental Oil and Gas Disclosures - Unaudited (Details Textual)
$ in Millions
 12 Months Ended
Dec. 31, 2019
USD ($)
MMBoe
Dec. 31, 2018
USD ($)
MMBoe
Dec. 31, 2017
USD ($)
Boe
MMBoe
Asset Retirement Obligation, Period Increase (Decrease) Due To Acquisitions Incurred and Revisions | $ $ 37.5 $ 20.3 $ 21.3
Seismic Costs | $ 7.8 1.5 0.5
Geological and Geophysical Costs | $ $ 5.7 $ 5.4 $ 4.2
Percentage of Non-operated Proved Developed Non-producing Reserves 10.70%    
Proved Undeveloped Reserve Net Energy Converted Outside of Five Years 2.5    
Percentage of Proved Undeveloped Reserves Expected To Be Developed 11.00%    
Present Value Discounted Percentage.   10.00%  
Barrel Equivalent [Member] | Proved Undeveloped Reserves [Member]      
Proved Developed and Undeveloped Reserve, Net (Energy), Ending Balance 23.6    
Changes Due To Price [Member]      
Proved Developed and Undeveloped Reserve, Revision of Previous Estimate (Energy)   2.3 3.4
Proved Developed and Undeveloped Reserve, Extension and Discovery (Energy) 10    
Changes at Ship Shoal 349 Field (Mahogany) [Member]      
Proved Developed and Undeveloped Reserve, Extension and Discovery (Energy) | Boe     3.5
Main Pass 286 Field [Member]      
Proved Developed and Undeveloped Reserve, Extension and Discovery (Energy) | Boe     1.5
Changes at the Viosca Knoll 823 [Member]      
Proved Developed and Undeveloped Reserve, Extension and Discovery (Energy)   1.3  
Ewing Bank 910 Field [Member]      
Proved Developed and Undeveloped Reserve, Extension and Discovery (Energy)   0.7  
Mississippi Canyon 800 (Gladden) Field [Member]      
Proved Developed and Undeveloped Reserve, Extension and Discovery (Energy) 0.9    
Mississippi Canyon 243 Field [Member]      
Wells Expected To Be Drilled, Year 2021    
Virgo Deepwater Fields [Member]      
Wells Expected To Be Drilled, Year 2022