Note 9 - Line of Credit (Details Textual) - USD ($) $ in Thousands	Dec. 08, 2017	Feb. 14, 2018	Feb. 13, 2018	Dec. 30, 2017	Dec. 31, 2016	Feb. 20, 2009
Long-term Line of Credit, Noncurrent				$ 27,279	$ 14,311
Citizens Bank of Pennsylvania [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity						$ 35,000
Line of Credit, Loan Covenants, Cash Dividend	$ 12,400
Line of Credit, Loan Covenants, Waiver Granted, Amount of Legal Settlement and Office Closure Expenses Excluded	1,300
Line of Credit, Loan Covenants, Waiver Granted, Consulting Expenses Excluded	1,000
Line of Credit, Loan Covenants, Waiver Granted, Goodwill Impairment Expenses Excluded	$ 4,600
Debt Instrument, Interest Rate, Effective Percentage				2.70%	2.30%
Long-term Line of Credit, Noncurrent				$ 27,300	$ 14,300
Letters of Credit Outstanding, Amount				800	$ 800
Line of Credit Facility, Remaining Borrowing Capacity				$ 6,900
Citizens Bank of Pennsylvania [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 40,000	$ 35,000
Citizens Bank of Pennsylvania [Member] | Letter of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity						$ 5,000