SECURITIES (Debt Securities, Held-to-Maturity, Credit Rating) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	$ 447,812	$ 421,807
U.S. Government and agency obligations
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	317	340
Municipal bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	391,583	370,998
Corporate bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	3,124	3,222
Mortgage-backed or related securities
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	52,788	47,247
Standard & Poor's, AAA to A Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	376,365	349,623
Standard & Poor's, AAA to A Rating | U.S. Government and agency obligations
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	0	0
Standard & Poor's, AAA to A Rating | Municipal bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	375,865	349,123
Standard & Poor's, AAA to A Rating | Corporate bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	500	500
Standard & Poor's, AAA to A Rating | Mortgage-backed or related securities
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	0	0
Standard & Poor's, Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	71,447	72,184
Standard & Poor's, Not Rated | U.S. Government and agency obligations
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	317	340
Standard & Poor's, Not Rated | Municipal bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	15,718	21,875
Standard & Poor's, Not Rated | Corporate bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	2,624	2,722
Standard & Poor's, Not Rated | Mortgage-backed or related securities
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	$ 52,788	$ 47,247