Stock-based compensation - Summary of assumptions used in determining fair value (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Weighted-average dividend yield	2.60%	2.60%	2.60%
Weighted-average volatility	31.00%	31.70%	32.90%
Volatilities, low end of range (as a percent)	28.50%	25.30%	29.20%
Volatilities, high end of range (as a percent)	35.50%	36.80%	45.80%
Risk-free interest rates, low end of range (as a percent)	3.92%	1.03%	0.06%
Risk-free interest rates, high end of range (as a percent)	5.03%	2.00%	1.41%
Weighted-average expected lives	7 years	8 years	8 years