Income taxes - Deferred income tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets:
Noncurrent deferred and refundable income taxes	$ 2,634	$ 2,047
Liabilities:
Other liabilities	454	471
Deferred income taxes—net	2,180	1,576
Deferred income tax assets:
Tax carryforwards	1,389	1,349
Research expenditures	1,350	949
Postemployment benefits	656	728
Employee compensation and benefits	634	459
Warranty reserves	325	282
Post sale discounts	253	159
Lease obligations	144	144
Inventory valuation	138	147
Allowance for credit losses	109	113
Other—net	197	376
Deferred income tax assets, total	5,195	4,706
Deferred income tax liabilities:
Capital and intangible assets, including lease basis differences	(1,312)	(1,401)
Undistributed profits, including translation adjustments	(401)	(344)
Other outside basis differences	(267)	(264)
Bond discount	(101)	(107)
Deferred income tax liabilities, total	(2,081)	(2,116)
Valuation allowance for deferred tax assets	(934)	(1,014)
Deferred income taxes—net	$ 2,180	$ 1,576