OTHER COMPREHENSIVE INCOME (LOSS)-AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, January 1	$ (14,164)	$ (9,401)
Change in other comprehensive income before reclassification	(1,238)	(5,958)
Amounts reclassified from accumulated other comprehensive income	698	1,195
Net current period other comprehensive income (loss)	(540)	(4,763)
Ending balance, December 31	(14,704)	(14,164)
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, January 1	(1,077)	9,053
Change in other comprehensive income before reclassification	3,371	(10,109)
Amounts reclassified from accumulated other comprehensive income	(36)	(21)
Net current period other comprehensive income (loss)	3,335	(10,130)
Ending balance, December 31	2,258	(1,077)
Retirement Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, January 1	(13,087)	(18,454)
Change in other comprehensive income before reclassification	(4,609)	4,151
Amounts reclassified from accumulated other comprehensive income	734	1,216
Net current period other comprehensive income (loss)	(3,875)	5,367
Ending balance, December 31	$ (16,962)	$ (13,087)