PENSION AND OTHER POST-EMPLOYMENT BENEFITS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Benefits
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Service cost	$ 175	$ 468
Interest cost	2,390	2,416
Expected return on plan assets	(4,615)	(3,612)
Amortization of prior service credit	0	0
Recognized actuarial loss (gain)	154	123
Net periodic benefit (income) cost	(1,896)	(605)
Pension Benefits | Cost of sales
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Net periodic benefit (income) cost	900	300
Pension Benefits | Selling, general and administrative expenses
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Net periodic benefit (income) cost	900	300
Other Benefits
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Service cost	0	0
Interest cost	43	49
Expected return on plan assets	0	0
Amortization of prior service credit	(371)	(280)
Recognized actuarial loss (gain)	1	(62)
Net periodic benefit (income) cost	$ (327)	$ (293)