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Income taxes - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Income Tax Disclosure [Abstract]      
Estimated annual effective tax rate   14.00%  
Statutory corporate tax rate   21.00%  
Amount of tax benefit for tax settlement $ 249   $ 249
Accrued interest related to uncertain tax position $ 46   $ 46