PENSION AND OTHER POSTRETIREMENT BENEFITS (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cost of sales
Components of the net periodic benefit cost
Net periodic benefit cost	$ 6,500	$ 7,300	$ 9,000
Selling, general, and administrative expenses
Components of the net periodic benefit cost
Net periodic benefit cost	5,200	5,300	5,800
Pension Benefits
Components of the net periodic benefit cost
Service cost	7,457	6,937	8,009
Interest cost	12,350	13,341	12,066
Expected return on plan assets	(14,455)	(15,743)	(13,912)
Amortization of prior service cost	0	10	14
Recognized actuarial loss	6,311	2,006	8,623
Settlement and curtailment related expense	0	6,060	0
Net periodic benefit cost	11,663	12,611	14,800
Other Benefits
Components of the net periodic benefit cost
Service cost	5	23	37
Interest cost	289	385	325
Expected return on plan assets	0	0	0
Amortization of prior service cost	(852)	(2,029)	(3,378)
Recognized actuarial loss	(144)	534	767
Settlement and curtailment related expense	0	449	0
Net periodic benefit cost	$ (702)	$ (638)	$ (2,249)