Employee plans - Schedule of Weighted-Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plans | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percentage)	2.85%	3.53%	4.50%
Expected long-term rate of return on assets (as a percentage)	6.07%	6.50%	6.80%
Weighted-average assumptions used to determine benefit obligations at December 31 were as follows:
Discount rate (as a percentage)	3.18%	2.85%	3.53%
Pension Plans | International Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percentage)	1.23%	1.82%	2.55%
Expected long-term rate of return on assets (as a percentage)	3.30%	3.50%	4.18%
Weighted-average assumptions used to determine benefit obligations at December 31 were as follows:
Discount rate (as a percentage)	1.73%	1.23%	1.82%
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate (as a percentage)	2.21%	5.13%	5.67%
Expected long-term rate of return on assets (as a percentage)	5.50%	5.50%	5.50%
Weighted-average assumptions used to determine benefit obligations at December 31 were as follows:
Discount rate (as a percentage)	2.70%	2.21%	5.13%