PENSION AND POSTRETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits
Components of net periodic benefit cost (credit)
Service cost	$ 498	$ 362	$ 991	$ 726
Interest cost	1,678	2,124	3,351	4,244
Expected return on plan assets	(2,413)	(2,501)	(4,813)	(4,996)
Amortization of prior service credit	(82)	(102)	(162)	(204)
Amortization of transition asset	(21)	(71)	(42)	(142)
Amortization of actuarial loss (gain)	784	436	1,562	871
Net periodic cost	444	248	887	499
Postretirement Benefits
Components of net periodic benefit cost (credit)
Service cost	3	3	6	6
Interest cost	18	22	37	44
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	0	0	0	0
Amortization of transition asset	0	0	0	0
Amortization of actuarial loss (gain)	(12)	(14)	(25)	(28)
Net periodic cost	$ 9	$ 11	$ 18	$ 22