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Financial instruments related to commodity contracts - Cash flow hedge (Details) - Derivative financial instruments related to commodity contracts - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Cash flow hedge      
Profit (Loss) recorded in other comprehensive income of the period $ 14 $ (14) $ 3
Recycled amount from other comprehensive income to the income statement of the period (1)   (3)
Ineffective portion of the cash flow hedges $ 0 $ 0 $ 0
Cash flow hedge      
Cash flow hedge      
Maximum maturity of most derivatives 1 year