Accumulated other comprehensive loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	$ 25,048	$ 22,466
Other comprehensive (loss) income before reclassifications	(80)	243
Amounts reclassified from Accumulated other comprehensive loss	(4)	(35)
Other comprehensive income (loss)	84	(208)
Balance at the end of the year	24,123	21,978
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(257)	(1,005)
Other comprehensive income (loss)	96	(199)
Balance at the end of the year	(353)	(806)
Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(187)	(856)
Balance at the end of the year	(288)	(627)
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(48)	(63)
Balance at the end of the year	(42)	(86)
Pension and Other Postretirement Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(22)	(86)
Balance at the end of the year	(23)	(93)
Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	1,044	859
Other comprehensive income (loss)	(12)	(9)
Balance at the end of the year	1,052	859
Accumulated foreign currency adjustment attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss)	(12)	(9)
Accumulated gain (loss), net, cash flow hedge, noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss)	0	0
Accumulated defined benefit plans adjustment attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss)	0	0
Accumulated foreign currency adjustment including portion attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	(89)	264
Amounts reclassified from Accumulated other comprehensive loss	0	(26)
Other comprehensive income (loss)	89	(238)
Cash flow hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	8	(21)
Amounts reclassified from Accumulated other comprehensive loss	(2)	(2)
Other comprehensive income (loss)	(6)	23
Pension and other postretirement plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	1	0
Amounts reclassified from Accumulated other comprehensive loss	(2)	(7)
Other comprehensive income (loss)	$ 1	$ 7