SHARE CAPITAL, OPTION PLANS AND SHARE-BASED PAYMENTS - Schedule of Share-Based Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 29,532	$ 26,770	$ 27,594
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	9,779	10,232	9,828
Performance Share Units | Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	5,997	3,461	3,553
Restricted Stock Units (RSUs) | Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	5,943	5,917	6,602
Restricted Stock Units (RSUs) | Other plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	174	175	936
Deferred Share Units (directors)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	3,345	3,133	2,921
Employee Share Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 4,294	$ 3,852	$ 3,754