Income taxes - Components of deferred tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Deferred loss and tax credit carryforwards	$ 207	$ 213
Accrued expenses	180	182
Stock compensation	106	109
Inventories and related reserves	105	109
Retirement costs for defined benefit and retiree health care	44	49
Other	3	0
Total deferred tax assets, before valuation allowance	645	662
Valuation allowance	(179)	(180)
Total deferred tax assets, after valuation allowance	466	482
Deferred tax liabilities:
Property, plant and equipment	(116)	(164)
International earnings	(44)	(62)
Acquisition-related intangibles and fair-value adjustments	(40)	(82)
Other	(13)	(55)
Total deferred tax liabilities	(213)	(363)
Net deferred tax asset	$ 253	$ 119