COMPREHENSIVE INCOME AND ACCUMULATED OTHER COMPREHENSIVE INCOME - Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accumulated other comprehensive (loss) income, net of tax
Beginning balance	$ 185,444	$ 94,193
Net current period other comprehensive income, net of tax	(1,343)	(1,554)
Ending balance	199,229	185,444
Reclassification adjustments for gains (loss) on securities transactions	2,100	36
Accumulated Other Comprehensive Income
Accumulated other comprehensive (loss) income, net of tax
Beginning balance	(167)	1,387
Other comprehensive (loss) income before reclassification, net of tax	51	(1,543)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(1,394)	(11)
Net current period other comprehensive income, net of tax	(1,343)	(1,554)
Ending balance	(1,510)	(167)
Unrealized gains (losses) on available for sale securities
Accumulated other comprehensive (loss) income, net of tax
Beginning balance	(1,150)	329
Other comprehensive (loss) income before reclassification, net of tax	3,267	(1,454)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(1,437)	(25)
Net current period other comprehensive income, net of tax	1,830	(1,479)
Ending balance	680	(1,150)
Unrealized gains (losses) on derivatives
Accumulated other comprehensive (loss) income, net of tax
Beginning balance	975	1,058
Other comprehensive (loss) income before reclassification, net of tax	(3,216)	(97)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	43	14
Net current period other comprehensive income, net of tax	(3,173)	(83)
Ending balance	(2,198)	975
Retirement benefit plan
Accumulated other comprehensive (loss) income, net of tax
Beginning balance	8
Other comprehensive (loss) income before reclassification, net of tax		8
Net current period other comprehensive income, net of tax		8
Ending balance	$ 8	$ 8