INVESTMENT SECURITIES - Investment Category of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value
Less than 12 Months	$ 54,913	$ 16,538
12 Months or More	3,288	0
Total	58,201	16,538
Unrealized Loss
Less than 12 Months	1,876	34
12 Months or More	149	0
Total	2,025	34
Obligations of states and political subdivisions
Fair Value
Less than 12 Months	398
12 Months or More	0
Total	398
Unrealized Loss
Less than 12 Months	2
12 Months or More	0
Total	2
Mortgage-backed securities
Fair Value
Less than 12 Months	54,515	16,538
12 Months or More	3,288	0
Total	57,803	16,538
Unrealized Loss
Less than 12 Months	1,874	34
12 Months or More	149	0
Total	$ 2,023	$ 34