ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Components and Related Income Tax Effects (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME
Unrealized holding gains on available for sale securities	$ 5,813	$ 5,531
Reclassification adjustments for losses realized in income	15
Income tax effect	(1,704)	(1,613)
Net change in unrealized gains on available for sale securities	4,124	3,918
Reclassification adjustments for amortization realized in income	138	128
Income tax effect	(40)	(38)
Net change in post-retirement obligation	98	90
Change in fair value of derivatives used for cash flow hedges	(9,510)	(1,597)
Reclassification adjustments for gains realized in income	(110)	(556)
Income tax effect	2,813	628
Net change in unrealized losses on cash flow hedges	(6,807)	(1,525)
Other comprehensive (loss) income	$ (2,585)	$ 2,483

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