Accounting policies - Property, plant and equipment, net (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Accounting Policies [Line items]
Property, Plant and Equipment, Estimated Useful Lives	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember
Interest capitalized	$ 0	$ 0
Buildings | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	40 years
Buildings | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	5 years
Plant and equipment | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	40 years
Plant and equipment | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	4 years
Distribution system | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	40 years
Distribution system | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	3 years
Office furniture, fixtures and equipment | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	10 years
Office furniture, fixtures and equipment | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	3 years
Vehicles | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	10 years
Vehicles | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	3 years
Lab equipment | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	10 years
Lab equipment | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	5 years