Income taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiry	$ 332
Operating Loss carryforwards, not subject to expiration	931
Tax credit carryforward, amount	2,115
Tax credit carryforward, amount, subject to expiration	74
Tax credit carryforward, amount, not subject to expiry	2,041
Valuation allowance	914	$ 737	$ 578	$ 507
Undistributed earnings	16,400
Unrecognized tax benefits that would impact effective tax rate	627	537
Accrued interest	84	68
Interest and penalties	14	$ 5	$ 12
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	1,295
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 32