FAIR VALUE DISCLOSURES AND REPORTING, THE FAIR VALUE OPTION AND FAIR VALUE MEASUREMENTS - Reconciliation of Activity for Assets Measured at Fair Value based on Significant Unobservable (Non-market) Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Bank-Issued Trust Preferred Securities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, January 1	$ 235	$ 408
Paydown	(55)	(273)
Unrealized gain (loss) included in comprehensive income	38	105
Balance at June 30	218	240
Municipal securities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, January 1	20,126	10,345
Purchases	4,189	7,003
Maturities, calls and paydowns	(4,185)	(302)
Transfers to Level 2		(6,293)
Unrealized gain (loss) included in comprehensive income	(26)	131
Balance at June 30	$ 20,104	$ 10,884