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Risk Management Activities - Credit Risk - Narrative (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Disclosure of Financial Risk Management [line items]        
Cash and cash equivalents $ 648.7 $ 769.4 $ 524.7 $ 886.8
Environmental trust funds 109.6 98.8 $ 88.1  
Loan advanced – contractor        
Disclosure of Financial Risk Management [line items]        
Financial assets (68.4)      
Loan advanced – contractor | Lifetime expected credit losses        
Disclosure of Financial Risk Management [line items]        
Financial assets $ (23.4) $ (3.9)    
Peru        
Disclosure of Financial Risk Management [line items]        
Percentage of cash receipts on revenue recognition 90.00%      
Percentage of cash receipts at the end of quotation period 10.00%      
Counter party exposure        
Disclosure of Financial Risk Management [line items]        
Percentage of maximum investment in financial institutions' equity 2.50%