ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Reclassification Adjustments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan.
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net of tax	$ (285)	$ (245)	$ (89)
Reclassification adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net of tax	285	245	20
Reclassification adjustments | Unrealized Gains (Losses) on Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Net losses (gains) on investment securities			(107)
Total before tax			(107)
Provision for income taxes			38
Net of tax			(69)
Reclassification adjustments | Pension Plan.
Reclassification Adjustment out of Accumulated Other Comprehensive Income
Compensation and benefits	437	377	137
Total before tax	437	377	137
Provision for income taxes	(152)	(132)	(48)
Net of tax	$ 285	$ 245	$ 89