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, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost	$ 531	$ 785	$ 693
Interest cost	1,367	1,350	1,278
Expected return on plan assets	(1,482)	(1,495)	(1,400)
Amortization of actuarial losses	762	887	419
Net periodic pension cost	$ 1,178	$ 1,527	$ 990