PENSION BENEFITS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components of net periodic benefit cost:
Service cost	$ 2,592	$ 2,082	$ 5,184	$ 4,164
Interest cost	2,072	2,028	4,144	4,056
Expected return on assets	(2,012)	(3,713)	(5,682)	(7,426)
Amortization of unrecognized transition amount	5	5	10	10
Recognized prior service cost	(192)	50	(384)	100
Recognized net loss	1,379	578	2,758	1,156
Net periodic benefit cost	$ 3,844	$ 1,030	$ 6,030	$ 2,060