Income taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiry	$ 893
Operating Loss carryforwards, not subject to expiration	690
Tax credit carryforward, amount, subject to expiration	88
Tax credit carryforward, amount, not subject to expiry	3,287
Valuation allowance	1,336	$ 1,059	$ 914	$ 737
Undistributed earnings	17,800
Unrecognized tax benefits that would impact effective tax rate	727	589
Accrued interest	101	101
Interest and penalties	8	$ 20	$ 14
Foreign tax jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	1,485
Tax credit carryforward, amount	3,188
Federal jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	57
Tax credit carryforward, amount	188
State jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 42