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Trade and Other Payables - Schedule of Derivative Financial Liabilities (Parenthetical) (Detail) - USD ($)
$ in Millions
Dec. 31, 2022
Dec. 31, 2020
Dec. 31, 2019
Disclosure of Detailed Information about Derivative Financial Libilities Explanatory [Line Items]      
Derivative financial liabilities   $ 21.8 $ 127.6
Australian Oil Deriavtive Contracts [Member] | Forecast [Member]      
Disclosure of Detailed Information about Derivative Financial Libilities Explanatory [Line Items]      
Financial liabilities oil derivative contracts $ 2.6    
Ghanaian Oil Deriavtive Contracts [Member] | Forecast [Member]      
Disclosure of Detailed Information about Derivative Financial Libilities Explanatory [Line Items]      
Financial liabilities oil derivative contracts $ 4.7    
Trade and other payable [member]      
Disclosure of Detailed Information about Derivative Financial Libilities Explanatory [Line Items]      
Derivative financial liabilities     $ 127.6