Customer Lists and Other Identifiable Intangible Assets, Net - Other Identifiable Intangible Assets (Detail) - Customer Lists and Other Identifiable Intangible Assets [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 30, 2018	Apr. 01, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Other identifiable intangible assets, cost	$ 25,288	$ 25,288
Less: Accumulated amortization	(9,266)	(8,806)
Total other identifiable intangible assets, net	$ 16,022	$ 16,482	$ 17,861	$ 18,320