Note 4 - Accounts Receivable, Transit Accounts Receivable and Transit Accounts Payable - Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 28, 2020	Dec. 28, 2019
Allowance for sales discounts and doubtful accounts	$ (1,867)	$ (1,725)
Accounts receivable, net	50,767	59,760
Billed Revenues [Member]
Accounts receivable, current	29,703	29,214
Unbilled Revenues [Member]
Accounts receivable, current	11,374	13,824
Work In Progress [Member]
Accounts receivable, current	4,170	4,352
Accounts Receivable Subject to Arbitration [Member]
Accounts receivable, current	$ 7,387	$ 14,095