Net Periodic Benefit Cost for Defined Benefit Pension Plan (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 303	$ 591
Interest cost	46	89
Expected return on plan assets	(38)	(75)
Amortization of prior service cost	41	82
Net periodic benefit cost	$ 352	$ 687