Commitments and contingencies (Details) - Environmental remediation $ in Millions	Sep. 30, 2026 USD ($)
Phillipsburg, New Jersey
Commitments and contingencies
Accrued environmental loss	$ 2.1
Accrued environmental loss, gross	$ 3.3
Phillipsburg, New Jersey | Minimum
Commitments and contingencies
Accrued environmental loss, discount rate	4.50%
Phillipsburg, New Jersey | Maximum
Commitments and contingencies
Accrued environmental loss, discount rate	5.70%
Gliwice, Poland
Commitments and contingencies
Accrued environmental loss	$ 0.9