Accumulated other comprehensive loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	$ 23,241	$ 21,116	$ 22,466	$ 21,288
Other comprehensive income (loss) before reclassifications	(35)	354	716	159
Amounts reclassified from Accumulated other comprehensive loss	(3)	(6)	(54)	(27)
Other comprehensive income (loss)	38	(348)	(662)	(132)
Balance at the end of the year	24,210	22,805	24,210	22,805
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(345)	(813)	(1,005)	(616)
Other comprehensive income (loss)	36	(314)	(624)	(117)
Balance at the end of the year	(381)	(499)	(381)	(499)
Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(147)	(617)	(856)	(439)
Balance at the end of the year	(202)	(288)	(202)	(288)
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(96)	(65)	(63)	(47)
Balance at the end of the year	(75)	(73)	(75)	(73)
Pension and Other Postretirement Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	(102)	(131)	(86)	(130)
Balance at the end of the year	(104)	(138)	(104)	(138)
Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the beginning of the year	896	390	859	434
Other comprehensive income (loss)	2	(34)	(38)	(15)
Balance at the end of the year	901	930	901	930
Accumulated foreign currency adjustment attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss)	2	(34)	(38)	(15)
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	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	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 income (loss) before reclassifications	(58)	363	725	205
Amounts reclassified from Accumulated other comprehensive loss	1	0	(33)	(39)
Other comprehensive income (loss)	57	(363)	(692)	(166)
Cash flow hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	23	(9)	(9)	(46)
Amounts reclassified from Accumulated other comprehensive loss	(2)	1	(3)	20
Other comprehensive income (loss)	(21)	8	12	26
Pension and other postretirement plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from Accumulated other comprehensive loss	(2)	(7)	(18)	(8)
Other comprehensive income (loss)	$ 2	$ 7	$ 18	$ 8