MARKETABLE SECURITIES - Narrative (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($) Position security	Sep. 30, 2020 USD ($) 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	4	4
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	$ 315,338,000	$ 315,338,000	$ 278,318,000
Number of securities sold | security	0	0