Defined contribution and defined benefit retirement plans - Weighted Average Rate Assumptions Used in Determining Net Periodic Pension Cost (Detail) - Defined benefit pension plans	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Foreign Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.90%	1.50%	1.00%
Increase in future compensation levels	2.70%	2.60%	2.60%
Long-term return on plan assets	4.60%	2.50%	2.40%
U S
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.30%	2.60%	2.20%
Long-term return on plan assets	5.00%	4.00%	4.00%