ACCUMULATED OTHER COMPREHENSIVE INCOME OR LOSS - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net gains on securities transactions	$ 908	$ 50
Pension and other employee benefits	1,675	1,729
Tax effect	1,316	1,126
Net of tax	2,707	2,276
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net of tax	(332)	193
Unrealized Gains and Losses on Securities Available for Sale [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net gains on securities transactions	(908)	(50)
Tax effect	343	19
Net of tax	(565)	(31)
Defined Benefit and Other Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Tax effect	(141)	(137)
Net of tax	233	224
Prior Service Costs [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Pension and other employee benefits	(22)	(22)
Actuarial Losses [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Pension and other employee benefits	$ 396	$ 383