Note 4 - Accounts Receivable, Transit Accounts Receivable and Transit Accounts Payable - Accounts Receivable (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Allowance for sales discounts and doubtful accounts	$ (1,496)	$ (1,402)
Accounts receivable, net	43,152	45,170
Billed Revenues [Member]
Accounts Receivable, Gross, Current	33,075	34,463
Unbilled Revenues [Member]
Accounts Receivable, Gross, Current	5,688	6,894
Work In Progress [Member]
Accounts Receivable, Gross, Current	$ 5,885	$ 5,215