Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Sep. 28, 2018	Dec. 29, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for contract losses and doubtful accounts	$ (3,912)	$ (3,526)
Total accounts receivable, net	122,911	110,100
Billed accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable	83,939	78,139
Unbilled accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable	$ 42,884	$ 35,487