Employee Benefit Plans - Components of Net Periodic Pension Cost for Defined Benefit Pension Plan and Retirement Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 785	$ 693	$ 843
Interest cost	1,350	1,278	1,160
Expected return on plan assets	(1,495)	(1,400)	(1,222)
Amortization of actuarial losses	887	419	1,093
Net periodic pension cost	$ 1,527	$ 990	$ 1,874