Income taxes (Details 6) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating loss and Tax credit carryforwards
Valuation allowance for deferred tax assets	$ 928	$ 915
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 264
U.S. state taxing jurisdictions
Operating loss and Tax credit carryforwards
Primary period of net operating loss carryforward expiration, years	20 years
State tax credit carryforward expiration, over period of years, and unlimited	15 years
U.S. state taxing jurisdictions | Primarily over the next 20 years
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	$ 1,320
Valuation allowance for deferred tax assets	172
U.S. state taxing jurisdictions | Expiration date next one to fifteen years
Operating loss and Tax credit carryforwards
Tax credit carryforwards	125
Non-U.S. taxing jurisdictions
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	4,375
Valuation allowance for deferred tax assets	750
Non-U.S. taxing jurisdictions | Expiring in 2020
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	104
Non-U.S. taxing jurisdictions | Expiring in 2021
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	53
Non-U.S. taxing jurisdictions | Expiring in 2022
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	81
Non-U.S. taxing jurisdictions | Expire between 2023-2025
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	59
Non-U.S. taxing jurisdictions | Expire between 2026-2040
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	451
Non-U.S. taxing jurisdictions | Unlimited
Operating loss and Tax credit carryforwards
Net operating loss carryforwards	$ 3,627