PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Benefits
Components of the net periodic benefit cost
Service cost	$ 2,002	$ 1,802
Interest cost	3,016	2,955
Expected return on plan assets	(3,478)	(3,131)
Amortization of prior service cost	4	4
Recognized actuarial loss	2,156	1,027
Net periodic benefit cost	3,700	2,657
Other Benefits
Components of the net periodic benefit cost
Service cost	9	12
Interest cost	81	114
Amortization of prior service cost	(844)	(844)
Recognized actuarial loss	192	246
Net periodic benefit cost	$ (562)	$ (472)