OTHER COMPREHENSIVE INCOME - RECLASSIFICATION (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Significant amounts reclassified out of each component of AOCI
Interest benefit (expense) on deposits	$ (3,647)	$ (6,903)	$ (9,949)	$ (13,651)
Interest benefit (expense) on FHLB advances	(822)	(4,062)	(2,470)	(6,792)
Total interest benefit (expense)	(4,886)	(11,718)	(13,307)	(22,052)
Income tax (benefit) expense	(3,793)	(3,176)	(10,674)	(10,636)
NET INCOME	15,804	18,007	42,501	47,523
Unrealized gain (loss) on cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Significant amounts reclassified out of each component of AOCI
Interest benefit (expense) on deposits	(38)	8	(55)	16
Interest benefit (expense) on FHLB advances	(41)	5	(53)	16
Total interest benefit (expense)	(79)	13	(108)	32
Income tax (benefit) expense	20	(3)	27	(7)
NET INCOME	$ (59)	$ 10	$ (81)	$ 25