BENEFIT PLANS Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Plans, Defined Benefit
Service cost	$ 3,032	$ 2,578	$ 6,010	$ 5,012
Interest cost	2,627	2,305	5,318	4,492
Expected return on plan assets	(1,189)	(1,290)	(2,414)	(2,506)
Amortization of prior service cost	(33)	21	(70)	41
Amortization of net loss	494	405	992	788
Net periodic benefit cost	4,931	4,019	9,836	7,827
Other Postretirement Benefit Plans, Defined Benefit
Service cost	18	16	37	32
Interest cost	118	139	235	277
Amortization of net loss	57	49	115	98
Net periodic benefit cost	$ 193	$ 204	$ 387	$ 407