Fair value measurement (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Level 1
Financial assets:
Investments subject to significant influence	$ 2,639	$ 2,189
Other investments	1,096	954
Total financial assets	3,735	3,143
Financial liabilities:
Total financial liabilities	0	0
Level 2
Financial assets:
Investments subject to significant influence	0	0
Other investments	267	267
Total financial assets	267	267
Financial liabilities:
Total financial liabilities	0	0
Level 3
Financial assets:
Investments subject to significant influence	0	0
Other investments	0	0
Total financial assets	0	0
Financial liabilities:
Total financial liabilities	$ 0	$ 0

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.