Components of Net Periodic Pension Cost (Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 2,062	$ 2,405	$ 3,048
Expected return on assets	(4,231)	(4,756)	(4,401)
Recognized net actuarial loss	2,718	1,803	1,917
Amortization of prior service (credit) cost	(1,555)	(1,555)	28
Settlement loss	792	1,204	0
Total net periodic pension (benefit) cost	$ (214)	$ (899)	$ 592