OTHER COMPREHENSIVE INCOME (LOSS)-AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, January 1	$ (7,501)	$ (23,454)
Change in other comprehensive income before reclassification	15,965	14,818
Amounts reclassified from accumulated other comprehensive income	1,300	1,135
Net current period other comprehensive income (loss)	17,265	15,953
Ending balance, December 31	9,764	(7,501)
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, January 1	14,893	(6,105)
Change in other comprehensive income before reclassification	19,444	21,031
Amounts reclassified from accumulated other comprehensive income	(175)	(33)
Net current period other comprehensive income (loss)	19,269	20,998
Ending balance, December 31	34,162	14,893
Retirement Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance, January 1	(22,394)	(17,349)
Change in other comprehensive income before reclassification	(3,479)	(6,213)
Amounts reclassified from accumulated other comprehensive income	1,475	1,168
Net current period other comprehensive income (loss)	(2,004)	(5,045)
Ending balance, December 31	$ (24,398)	$ (22,394)