SECURITIES (Debt Securities, Held-to-Maturity, Credit Rating) (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	$ 429,135
U.S. Government and agency obligations
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	341
Municipal bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	377,019
Corporate bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	3,254
Mortgage-backed or related securities
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	48,521
Standard & Poor's, AAA to A Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	354,148
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
Standard & Poor's, AAA to A Rating | Municipal bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	353,648
Standard & Poor's, AAA to A Rating | Corporate bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	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
Standard & Poor's, Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	74,987
Standard & Poor's, Not Rated | U.S. Government and agency obligations
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	341
Standard & Poor's, Not Rated | Municipal bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	23,371
Standard & Poor's, Not Rated | Corporate bonds
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	2,754
Standard & Poor's, Not Rated | Mortgage-backed or related securities
Financing Receivable, Credit Quality Indicator [Line Items]
Debt securities, held-to-maturity	$ 48,521