Income taxes (Details 6) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating loss and Tax credit carryforwards
Valuation allowance for deferred tax assets	$ 1,009	$ 928
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 350
U.S. state taxing jurisdictions
Operating loss and Tax credit carryforwards
Primary period of net operating loss carryforward expiration, years	twenty years
State tax credit carryforward expiration, over period of years, and unlimited	fifteen years
U.S. state taxing jurisdictions | Primarily over the next 20 years
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	$ 1,399
Valuation allowance for deferred tax assets	183
U.S. state taxing jurisdictions | Expiration date next one to fifteen years
Operating loss and Tax credit carryforwards
Tax credit carryforwards	139
Non-U.S. taxing jurisdictions
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	4,963
Valuation allowance for deferred tax assets	803
Non-U.S. taxing jurisdictions | 2021
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	45
Non-U.S. taxing jurisdictions | 2022
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	81
Non-U.S. taxing jurisdictions | 2023
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	10
Non-U.S. taxing jurisdictions | 2024-2026
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	79
Non-U.S. taxing jurisdictions | 2027-2041
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	819
Non-U.S. taxing jurisdictions | Unlimited
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	$ 3,929