Employee Benefit Plans - Components of Net Periodic Pension Cost for Defined Benefit Pension Plan and Retirement Plan (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Retirement Benefits [Abstract]
Service cost	$ 150	$ 133	$ 450	$ 398
Interest cost	317	332	951	997
Expected return on plan assets	(446)	(382)	(1,338)	(1,147)
Amortization of actuarial losses	185	202	557	607
Net periodic pension cost	$ 206	$ 285	$ 620	$ 855