FAIR VALUE MEASUREMENTS - Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 626,341	$ 663,230
US Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	295,657	321,969
US Government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	101,669	99,661
Private label
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	18,499	19,533
Obligations of states and political subdivisions thereof
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	137,579	142,006
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	72,937	80,061
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
Derivative assets	0
Derivative liabilities	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	626,341	663,230
Derivative assets	24,933	6,791
Derivative liabilities	(28,032)	(8,102)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
Derivative assets	93	59
Derivative liabilities	(73)	(84)
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	25,026	6,850
Derivative liabilities	(28,105)	(8,186)
Recurring | US Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	295,657	321,969
Recurring | US Government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	101,669	99,661
Recurring | Private label
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	18,499	19,533
Recurring | Obligations of states and political subdivisions thereof
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	137,579	142,006
Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	72,937	80,061
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Derivative liabilities	0
Recurring | Level 1 | US Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	0
Recurring | Level 1 | US Government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	0
Recurring | Level 1 | Private label
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	0
Recurring | Level 1 | Obligations of states and political subdivisions thereof
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
Recurring | Level 1 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	24,933	6,791
Derivative liabilities	(28,032)	(8,102)
Recurring | Level 2 | US Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	295,657	321,969
Recurring | Level 2 | US Government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	101,669	99,661
Recurring | Level 2 | Private label
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	18,499	19,533
Recurring | Level 2 | Obligations of states and political subdivisions thereof
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	137,579	142,006
Recurring | Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	72,937	80,061
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	93	59
Derivative liabilities	(73)	$ (84)
Recurring | Level 3 | US Government-sponsored enterprises
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	0
Recurring | Level 3 | US Government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	0
Recurring | Level 3 | Private label
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage-backed securities available for sale	0
Recurring | Level 3 | Obligations of states and political subdivisions thereof
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	0
Recurring | Level 3 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 0