Annual report pursuant to Section 13 and 15(d)

Income Taxes (Income Tax Years Subject To Examination By Major Tax Jurisdictions) (Details)

v3.20.1
Income Taxes (Income Tax Years Subject To Examination By Major Tax Jurisdictions) (Details) - Minimum [Member]
 12 Months Ended
Dec. 31, 2019
United States  
Income Tax Examination [Line Items]  
Income tax examination year under examination 2009
Gabon [Member]  
Income Tax Examination [Line Items]  
Income tax examination year under examination 2015