DEBT (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2012
Long-term debt disclosure
Total debt	$ 630,252		$ 630,252		$ 322,110
Repayment of outstanding borrowings			50,000
Convertible notes due 2019, net
Long-term debt disclosure
Total debt	330,252		330,252		$ 322,110
Aggregate principal amount of convertible senior notes issued						$ 370,000
Interest rate on convertible senior notes (as a percent)						2.875%
Interest expense recognized	5,700	$ 5,600	17,100	$ 16,500
Revolving credit facility
Long-term debt disclosure
Total debt	300,000		300,000
Maximum availability under the revolving credit facility	650,000		650,000
Available under the revolving credit facility	350,000		350,000
Outstanding amount under credit facility	300,000		$ 300,000
Repayment of outstanding borrowings	$ 50,000
Revolving credit facility | LIBOR
Long-term debt disclosure
Revolving credit facility, basis spread on interest rate (as a percent)			2.25%
Effective interest rate (as percent)	2.87%		2.87%
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%