Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Accounts Notes And Loans Receivable [Line Items]
Allowance for contract losses and doubtful accounts	$ (5,218)	$ (4,066)
Total accounts receivable, net	128,333	105,814
Billed accounts receivable
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable	90,980	73,905
Unbilled accounts receivable
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable	$ 42,571	$ 35,975