OTHER COMPREHENSIVE INCOME - RECLASSIFICATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Significant amounts reclassified out of each component of AOCI
Interest benefit (expense) on deposits	$ (6,302)	$ (6,748)
Interest benefit (expense) on FHLB advances	(1,648)	(2,730)
Total interest benefit (expense)	(8,421)	(10,334)
Income tax (benefit) expense	(6,881)	(7,460)
NET INCOME	26,697	29,516
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	(12)	8
Interest benefit (expense) on FHLB advances	(17)	11
Total interest benefit (expense)	(29)	19
Income tax (benefit) expense	7	(4)
NET INCOME	$ (22)	$ 15