Note 10 - Debt and Other Financing Agreements (Details Textual) - USD ($) $ in Thousands								12 Months Ended			45 Months Ended
	Nov. 10, 2017	Mar. 23, 2016	Sep. 15, 2015	Aug. 08, 2014	Jun. 13, 2014	May 22, 2014	Mar. 24, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Proceeds from Issuance of Long-term Debt								$ 2,078	$ 610	$ 1,097
Repayments of Long-term Debt								2,082	3,120	$ 1,455
Banc of America Leasing and Capital [Member] | Equipment Loan Arrangement [Member] | Line of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity								12,800			$ 12,800
Debt Instrument, Collateral Amount								6,900			6,900
Proceeds from Issuance of Long-term Debt	$ 2,100	$ 610	$ 1,100	$ 1,000	$ 3,000	$ 1,900	$ 1,100				10,800
Repayments of Long-term Debt								2,100	$ 3,100
Line of Credit Facility, Remaining Borrowing Capacity								$ 1,900			$ 1,900
Debt Instrument, Interest Rate During Period								3.00%
Interest Expense								$ 72
Debt, Weighted Average Interest Rate								3.30%			3.30%
Banc of America Leasing and Capital [Member] | Equipment Loan Arrangement, Loans prior to 2017 [Member] | Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate								2.00%
Banc of America Leasing and Capital [Member] | Equipment Loan Arrangement, Loan Made After October 2017 [Member] | Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate								1.75%