SHAREHOLDERS’ EQUITY AND COMPENSATION PLANS - Changes in Accumulated Other Comprehensive Income After-tax By Component (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,092,497	$ 846,436	$ 1,078,975	$ 867,185
Ending balance	1,118,301	867,963	1,118,301	867,963
Net Unrealized Gain on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	11,400	25,538	22,320	14,977
Net change	2,850	10,984	(8,070)	21,545
Transfer from available-for-sale to held-to-maturity		(8,650)		(8,650)
Ending balance	14,250	27,872	14,250	27,872
Unamortized Gain (Loss) on Held-to-Maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	18,159	4,778	19,308	4,934
Net change	(837)	(329)	(1,986)	(485)
Transfer from available-for-sale to held-to-maturity		8,650		8,650
Ending balance	17,322	13,099	17,322	13,099
Net Unrealized Gain (Loss) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,382)	(7,219)	(4,508)	(2,162)
Net change	82	(943)	1,208	(6,000)
Transfer from available-for-sale to held-to-maturity		0		0
Ending balance	(3,300)	(8,162)	(3,300)	(8,162)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	26,177	23,097	37,120	17,749
Net change	2,095	9,712	(8,848)	15,060
Transfer from available-for-sale to held-to-maturity		0		0
Ending balance	$ 28,272	$ 32,809	$ 28,272	$ 32,809