Summary of changes in outstanding options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Outstanding options, shares	63,440
Outstanding options, weighted average exercise price	$ 39.99
Outstanding remaining term	3 years 6 months 1 day
Share-Based Payment Arrangement, Option [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Outstanding options, shares	63,440	88,295	104,755	120,089
Outstanding options, weighted average exercise price	$ 39.99	$ 40.33	$ 37.93	$ 35.33
Outstanding remaining term	3 years 6 months	4 years 4 months 24 days	4 years 9 months 17 days	5 years 3 months 18 days
Options outstanding, weighted average fair value	$ 981	$ 1,271	$ 1,416	$ 1,531
Shares exercised	(24,855)	(16,460)	(15,334)
Exercises, weighted average exercise price	$ 41.21	$ 25.07	$ 17.54
Exercised, weighted average fair value	$ (290)	$ (145)	$ (115)
Options exercisable, shares	63,440
Exercisable, weighted average exercise price	$ 39.99
Exercisable remaining term	3 years 6 months
Exercisable, weighted average fair value	$ 981
Options vested, shares	3,990
Vested, weighted average fair value	$ 65