PENSION AND OTHER POSTRETIREMENT BENEFITS (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cost of sales
Components of the net periodic benefit cost
Net periodic benefit cost	$ 7,300
Selling, general, and administrative expenses
Components of the net periodic benefit cost
Net periodic benefit cost	5,300
Pension Benefits
Components of the net periodic benefit cost
Service cost	6,937	8,009	7,209
Interest cost	13,341	12,066	11,819
Expected return on plan assets	(15,743)	(13,912)	(12,523)
Amortization of prior service cost	10	14	14
Recognized actuarial loss	2,006	8,623	4,108
Settlement and curtailment related expense	6,060	0	0
Net periodic benefit cost	12,611	14,800	10,627
Other Benefits
Components of the net periodic benefit cost
Service cost	23	37	50
Interest cost	385	325	457
Expected return on plan assets	0	0	0
Amortization of prior service cost	(2,029)	(3,378)	(3,375)
Recognized actuarial loss	534	767	983
Settlement and curtailment related expense	449	0	0
Net periodic benefit cost	$ (638)	$ (2,249)	$ (1,885)