MARKETABLE SECURITIES (Schedule of Contractual Maturities) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2016
12 months or less, Fair Value	$ 51,124	$ 118,680	$ 72,269
12 months or less, Gross unrealized losses	(66)	(567)	(148)
Greater than 12 months, Fair Value	39,373	74,256	103,116
Greater than 12 months, Gross unrealized losses	(180)	(308)	(443)
Sales and maturities of available-for-sale marketable securities	32,782	129,345	80,269	$ 6,350
Loss	$ 25,381	128,046	$ 84,172	$ 76,609
Marketable securities [Member]
Sales and maturities of available-for-sale marketable securities		44,848
Loss		$ 137