MARKETABLE SECURITIES - Schedule of Proceeds from Sales of Available for Sale Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Sale of Marketable Securities [Abstract]
Proceeds from sales	$ 0	$ 3,957	$ 411,796
Gross gains	0	0	4
Gross losses	$ 0	$ (22)	$ (54)