Variable interest entities - Schedule of results of variable interest entities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Variable Interest Entity [Line Items]
Gross profit	$ 1,807	$ 1,619
Net loss	116	(28)
Net cash used in operating activities	(712)	(671)
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Total revenues	96	115
Total cost of revenues	(87)	(114)
Gross profit	9	1
Net loss	(9)	(12)
Net cash used in operating activities	$ (6)	$ (7)