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Equity (Share-based Payments to Employees, Non-marketable Options, Movement) (Details) - Non-marketable options [Member]
Pure in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Balance as at start of year 27 30
Granted during the year 1  
Expired during the year   (2)
Exercised during the year (16) (1)
Balance as at end of year 12 27