MARKETABLE SECURITIES - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) Position security	Jun. 30, 2019 security	Jun. 30, 2020 USD ($) Position security	Dec. 31, 2019 USD ($)
Investments Debt And Equity Securities [Abstract]
Allowance for credit losses for available for sale debt securities	$ 0		$ 0
Other than temporary impairment losses on debt securities related to credit losses				$ 0
Number of investment in an unrealized loss position | Position	2		2
Percentage of unrealized loss exceeds book value			20.00%
Number of securities other than agencies amount | security			0
Fair value of securities pledged as collateral	$ 306,846,000		$ 306,846,000	$ 278,318,000
Number of securities sold | security	0	0