PENSION AND POSTRETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits
Components of net periodic benefit cost (credit)
Service cost	$ 559	$ 493
Interest cost	1,672	1,673
Expected return on plan assets	(2,309)	(2,400)
Amortization of prior service credit	(63)	(80)
Amortization of transition asset	(77)	(21)
Amortization of loss (gain)	943	778
Net periodic cost	725	443
Postretirement Benefits
Components of net periodic benefit cost (credit)
Service cost	3	3
Interest cost	19	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)	(14)	(13)
Net periodic cost	$ 8	$ 9