DEBT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2012
Long-term debt disclosure
Principal	$ 370,000		$ 370,000		$ 370,000
Unamortized Discount	(2,844)		(2,844)		(12,764)
Debt Issuance Costs	(4,241)		(4,241)		(6,209)
Total debt	362,915		362,915		351,027
2019 Notes
Long-term debt disclosure
Principal	370,000		370,000		370,000
Unamortized Discount	(2,844)		(2,844)		(12,764)
Debt Issuance Costs	(290)		(290)		(1,316)
Total debt	366,866		366,866		355,920
Principal amount of debt issued						$ 370,000
Interest rate on convertible senior notes (as a percent)						2.875%
Interest expense recognized	6,300	$ 6,100	18,900	$ 18,300
Credit Facility
Long-term debt disclosure
Debt Issuance Costs	(3,951)		(3,951)		$ (4,893)
Interest expense recognized	300	$ 1,300	900	$ 4,900
Maximum availability under the revolving credit facility	1,000,000		1,000,000
Outstanding amount under credit facility	0		0
Available under the revolving credit facility	$ 1,000,000		$ 1,000,000