Summary of Components of Net Periodic Benefit Cost for Domestic Pension Plan (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
Components of net periodic benefit cost
Interest cost	$ 648	$ 646	$ 1,296	$ 1,292
Expected return on assets	(640)	(662)	(1,280)	(1,324)
Amortization of actuarial loss	223	140	447	280
Net periodic benefit cost	$ 231	$ 124	$ 463	$ 248