Financial instruments - Financial assets and liabilities measured at fair value (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Jun. 30, 2022
Assets:
Equity securities		$ 13,038
Derivatives	$ 61,879	42,771
Liabilities:
Derivatives	48,592	1,022,655
Quoted Prices In Active Markets (Level 1)
Assets:
Equity securities		13,038
Derivatives	0	0
Liabilities:
Derivatives	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Equity securities		0
Derivatives	61,879	42,771
Liabilities:
Derivatives	48,592	1,022,655
Significant Unobservable Inputs (Level 3)
Assets:
Equity securities		0
Derivatives	0	0
Liabilities:
Derivatives	$ 0	$ 0