DEBT (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016	Jun. 30, 2012
Long-term debt disclosure
Principal	$ 715,000		$ 715,000		$ 645,000
Unamortized Discount	(31,194)		(31,194)		(36,943)
Debt Issuance Costs	(6,377)		(6,377)		(7,372)
Total debt	677,429		677,429		600,685
Convertible notes due 2019
Long-term debt disclosure
Principal	370,000		370,000		370,000
Unamortized Discount	(31,194)		(31,194)		(36,943)
Debt Issuance Costs	(3,295)		(3,295)		(3,934)
Total debt	335,511		335,511		329,123
Aggregate principal amount of convertible senior notes issued						$ 370,000
Interest rate on convertible senior notes (as a percent)						2.875%
Interest expense recognized	5,900	$ 5,700	11,700	$ 11,300
Revolving credit facility
Long-term debt disclosure
Principal	345,000		345,000		275,000
Debt Issuance Costs	(3,082)		(3,082)		(3,438)
Total debt	341,918		341,918		$ 271,562
Interest expense recognized	2,300	$ 2,500	4,300	$ 3,000
Maximum availability under the revolving credit facility	650,000		650,000
Outstanding amount under credit facility	345,000		345,000
Available under the revolving credit facility	$ 305,000		$ 305,000
Revolving credit facility | LIBOR
Long-term debt disclosure
Revolving credit facility, basis spread on interest rate (as a percent)			1.75%
Effective interest rate (as percent)	2.63%		2.63%
Revolving credit facility | Minimum | LIBOR
Long-term debt disclosure
Revolving credit facility, basis spread on interest rate (as a percent)			1.25%
Revolving credit facility | Maximum | LIBOR
Long-term debt disclosure
Revolving credit facility, basis spread on interest rate (as a percent)			3.00%