Hedging transactions and derivative financial instruments Hedging transactions and derivative financial instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Reclassification from AOCI	$ (407)	$ (172)	$ (30)
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative [Line Items]
Reclassification from AOCI	(361)	(27)	$ 0
Foreign currency contracts | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative [Line Items]
Reclassification from AOCI	(359)	(27)
Interest rate swaps | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative [Line Items]
Reclassification from AOCI	(2)	(1)
Net investment hedging | Foreign currency contracts
Derivative [Line Items]
Derivative, notional amount outstanding	2,000	$ 1,000
Derivative, notional amount, entered into during period	$ 1,000