PENSION AND POSTRETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Benefits
Components of net periodic benefit cost (credit)
Service cost	$ 487	$ 559
Interest cost	1,498	1,672
Expected return on plan assets	(2,110)	(2,309)
Amortization of prior service credit	(76)	(63)
Amortization of transition asset	0	(77)
Amortization of loss (gain)	932	943
Net periodic cost	731	725
Postretirement Benefits
Components of net periodic benefit cost (credit)
Service cost	3	3
Interest cost	18	19
Expected return on plan assets	0	0
Amortization of prior service credit	0	0
Amortization of transition asset	0	0
Amortization of loss (gain)	(11)	(14)
Net periodic cost	$ 10	$ 8