RETIREMENT AND POSTRETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Distributions to Retired Participants [Abstract]
Retirement distributions	$ 0	$ 0	$ 0	$ 0
Retirement Plans [Member] | BMP, Employee and Outside Director Retirement Plans [Member]
Net Periodic Benefit Cost [Abstract]
Service cost	0	0	0	0
Interest cost	241	312	482	625
Expected return on assets	(428)	(382)	(856)	(764)
Unrecognized past service liability	0	0	0	0
Amortization of unrealized loss (gain)	274	243	548	486
Net periodic cost	87	173	174	347
Retirement Plans [Member] | Employee Retirement Plan [Member]
Retirement and Postretirement Plans [Abstract]
Planned contributions/benefit payments	58		58
Actual contributions/benefit payments	0		0
Retirement Plans [Member] | Outside Director Retirement Plan [Member]
Retirement and Postretirement Plans [Abstract]
Planned contributions/benefit payments	263		263
Actual contributions/benefit payments	56		112
Retirement Plans [Member] | Postretirement Plan [Member]
Retirement and Postretirement Plans [Abstract]
Planned contributions/benefit payments	109		109
Actual contributions/benefit payments	137		274
Retirement Plans [Member] | BMP Retirement Plan [Member]
Retirement and Postretirement Plans [Abstract]
Planned contributions/benefit payments	569		569
Actual contributions/benefit payments	57		95
Other Postretirement Plan [Member] | Postretirement Plan [Member]
Net Periodic Benefit Cost [Abstract]
Service cost	0	0	0	0
Interest cost	10	13	20	27
Expected return on assets	0	0	0	0
Unrecognized past service liability	(2)	(2)	(4)	(4)
Amortization of unrealized loss (gain)	0	(3)	0	(6)
Net periodic cost	$ 8	$ 8	$ 16	$ 17