MARKETABLE SECURITIES - Sale of Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Sale Of Marketable Securities [Abstract]
Proceeds from sales	$ 0	$ 102,356	$ 3,957	$ 111,813
Gross gains	0	4	0	4
Gross losses	$ 0	$ (3)	$ (22)	$ (54)