Employee Benefit Plans - Summary of Employee Benefit Plans (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
Employee Benefit Plans [Line Items]
Interest cost	$ 234	$ 250	$ 724	$ 751
Expected return on plan assets	(276)	(296)	(855)	(866)
Amortization of net actuarial loss	222	197	688	591
Net periodic pension expense	$ 180	$ 151	$ 557	$ 476