Financial instruments - Fair value of derivative instruments reported in consolidated balance sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Sep. 30, 2023
Cross-currency swap contracts
Net investment hedges
Cross-currency swap contracts, assets	$ 7,049	$ 16,325
Cross-currency swap contracts, liability	$ 2,089	208
Other derivative contracts
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Investments and other assets		Investments and other assets
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities		Other liabilities
Forward exchange contracts
Other derivative contracts
Other derivative contracts, assets	$ 66	7,625
Other derivative contracts, liabilities	$ 6,065	$ 72
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Non-trade and notes receivable		Non-trade and notes receivable
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other accrued liabilities		Other accrued liabilities