DERIVATIVES - Additional Information (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($) N	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) N	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Derivative [Line Items]
Net interest income (expense)	$ 31,735,000	$ 32,149,000	$ 31,971,000	$ 31,747,000	$ 30,914,000	$ 30,085,000	$ 29,268,000	$ 30,007,000	$ 127,602,000	$ 120,274,000	$ 115,163,000
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount	$ 270,000,000.0				$ 245,000,000.0				270,000,000.0	245,000,000.0
Net interest income (expense)									(3,700,000)	953,000
Unrealized after-tax gain of accumulated other comprehensive income (loss)				$ 26,000			$ 189,000
Interest income									$ 89,000	$ 223,000
Derivative number of instruments terminated | N				3			4