DEBT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017	Jun. 30, 2012
Long-term debt disclosure
Principal	$ 445,000		$ 445,000		$ 620,000
Unamortized Discount	(15,963)		(15,963)		(25,251)
Debt Issuance Costs	(6,764)		(6,764)		(8,579)
Total debt	422,273		422,273		586,170
Repayment of revolving credit facility			175,000	$ 45,000
2019 Notes
Long-term debt disclosure
Principal	370,000		370,000		370,000
Unamortized Discount	(15,963)		(15,963)		(25,251)
Debt Issuance Costs	(1,653)		(1,653)		(2,646)
Total debt	352,384		352,384		342,103
Principal amount of debt issued						$ 370,000
Interest rate on convertible senior notes (as a percent)						2.875%
Interest expense recognized	6,100	$ 5,900	18,300	17,600
Credit Facility
Long-term debt disclosure
Principal	75,000		75,000		250,000
Debt Issuance Costs	(5,111)		(5,111)		(5,933)
Total debt	69,889		69,889		$ 244,067
Interest expense recognized	1,300	$ 2,900	4,900	$ 7,200
Maximum availability under the revolving credit facility	1,000,000		1,000,000
Outstanding amount under credit facility	75,000		75,000
Available under the revolving credit facility	$ 925,000		$ 925,000
Effective interest rate (as percent)	3.52%		3.52%
Repayment of revolving credit facility	$ 75,000		$ 175,000
LIBOR | Credit Facility
Long-term debt disclosure
Basis spread on interest rate (as a percent)			1.50%