BENEFIT PLANS Components of Net Periodic Benefit Cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Plans, Defined Benefit
Service cost	$ 3,004	$ 2,799	$ 9,014	$ 7,811
Interest cost	2,608	2,453	7,926	6,945
Expected return on plan assets	(1,180)	(1,350)	(3,594)	(3,856)
Amortization of prior service cost	(34)	20	(104)	61
Amortization of net loss	486	407	1,478	1,195
Net periodic benefit cost	4,884	4,329	14,720	12,156
Other Postretirement Benefit Plans, Defined Benefit
Service cost	18	16	55	48
Interest cost	117	137	352	414
Amortization of net loss	58	49	173	147
Net periodic benefit cost	$ 193	$ 202	$ 580	$ 609