PENSION BENEFITS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Components of net periodic benefit cost:
Service cost	$ 2,068	$ 1,898	$ 7,252	$ 6,062
Interest cost	1,934	2,214	6,078	6,270
Expected return on assets	(2,765)	(3,745)	(8,447)	(11,171)
Amortization of unrecognized transition amount	3	4	13	14
Recognized prior service cost	(192)	52	(576)	152
Recognized net loss	893	891	3,651	2,047
Net periodic benefit cost	$ 1,941	$ 1,314	$ 7,971	$ 3,374