Financial Instruments - Summary of financial assets and liabilities that were measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 7,901	$ 7,533
Derivatives	7,561	38,244
Derivatives	34,995	4,512
Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments measured at net asset value		9,728
Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	7,901	7,533
Derivatives	0	0
Derivatives	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Derivatives	7,561	38,244
Derivatives	34,995	4,512
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0	0
Derivatives	0	0
Derivatives	$ 0	$ 0