COMMERCIAL PAPER AND INVESTMENT SECURITIES (Schedule of Investments by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Jun. 30, 2019
AVAILABLE FOR SALE, Amortized cost
Due in one year or less	$ 46,960
Due after one through five years	117,814
Due after five through ten years
Due after ten years
Total	164,774
AVAILABLE FOR SALE, Fair value
Due in one year or less	46,185
Due after one through five years	112,146
Due after five through ten years
Due after ten years
Total	158,331
HELD TO MATURITY, Amortized cost
Due in one year or less	750
Due after one through five years	2,745
Due after five through ten years
Due after ten years
Total	3,495	$ 3,995
HELD TO MATURITY, Fair value
Due in one year or less	759
Due after one through five years	2,866
Due after five through ten years
Due after ten years
Total	$ 3,625	$ 4,080