MARKETABLE SECURITIES - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Position security	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 security
Debt Securities, Available-for-sale [Line Items]
Debt securities impairment on allowance for credit losses	$ 0
Other than temporary impairment losses on debt securities related to credit losses		$ 0
Number of investment in an unrealized loss position | Position	7
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	$ 314,962,000	$ 278,318,000
Number of held-to-maturity securities sold | security	0	0	0
Mortgage Backed Securities or Collateralized Mortgage Obligations
Debt Securities, Available-for-sale [Line Items]
Number of investment in an unrealized loss position | Position	6