DEBT (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Jun. 30, 2012
Long-term debt disclosure
Principal	$ 570,000		$ 620,000
Unamortized Discount	(22,206)		(25,251)
Debt Issuance Costs	(8,022)		(8,579)
Total debt	539,772		586,170
Repayment of revolving credit facility	50,000
Borrowings from revolving credit facility		$ 70,000
2019 Notes
Long-term debt disclosure
Principal	370,000		370,000
Unamortized Discount	(22,206)		(25,251)
Debt Issuance Costs	(2,318)		(2,646)
Total debt	345,476		342,103
Principal amount of debt issued				$ 370,000
Interest rate on convertible senior notes (as a percent)				2.875%
Interest expense recognized	6,000	5,800
Credit Facility
Long-term debt disclosure
Principal	200,000		250,000
Debt Issuance Costs	(5,704)		(5,933)
Total debt	194,296		$ 244,067
Interest expense recognized	1,800	$ 1,900
Maximum availability under the revolving credit facility	1,000,000
Outstanding amount under credit facility	200,000
Available under the revolving credit facility	$ 800,000
Effective interest rate (as percent)	3.07%
Repayment of revolving credit facility	$ 50,000
LIBOR | Credit Facility
Long-term debt disclosure
Basis spread on interest rate (as a percent)	1.75%