SHAREHOLDERS’ EQUITY AND COMPENSATION PLANS - Changes in Accumulated Other Comprehensive Income After-tax By Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,118,301	$ 867,963	$ 1,078,975	$ 867,185
Ending balance	1,439,635	882,267	1,439,635	882,267
Net Unrealized Gain on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	14,250	27,872	22,320	14,977
Net change	(7,870)	(220)	(15,940)	21,325
Transfer from available-for-sale to held-to-maturity				(8,650)
Ending balance	6,380	27,652	6,380	27,652
Unamortized Gain (Loss) on Held-to-Maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	17,322	13,099	19,308	4,934
Net change	(805)	(705)	(2,791)	(1,190)
Transfer from available-for-sale to held-to-maturity				8,650
Ending balance	16,517	12,394	16,517	12,394
Net Unrealized Gain (Loss) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,300)	(8,162)	(4,508)	(2,162)
Net change	305	624	1,513	(5,376)
Transfer from available-for-sale to held-to-maturity				0
Ending balance	(2,995)	(7,538)	(2,995)	(7,538)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	28,272	32,809	37,120	17,749
Net change	(8,370)	(301)	(17,218)	14,759
Transfer from available-for-sale to held-to-maturity				0
Ending balance	$ 19,902	$ 32,508	$ 19,902	$ 32,508