Note 13 - Debt (Details Textual)				12 Months Ended
	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 22, 2011 USD ($)	Jun. 30, 2018 USD ($)
Line of Credit Facility, Maximum Borrowing Capacity	$ 23,000,000
Line of Credit Facility, Interest Rate During Period				3.33%
Minimum Consolidated Cash and Liquid Investments Pursuant to New Loan and Security Agreement	$ 10,000,000
Long-term Line of Credit, Total				$ 12,900,000
Line of Credit Facility, Commitment Fee Percentage				0.25%
Line of Credit Facility, Current Borrowing Capacity				$ 22,100,000
Line of Credit Facility, Remaining Borrowing Capacity				9,200,000
Notes Payable to Banks [Member] | Santander Bank and Bradesco Bank [Member]
Debt Instrument, Face Amount		$ 3,500,000
Notes Payable to Banks [Member] | Santander Bank [Member]
Debt Instrument, Face Amount		$ 1,500,000
Debt Instrument, Term		180 days
Debt Instrument, Interest Rate, Stated Percentage		4.19%
Notes Payable to Banks [Member] | Bradesco Bank [Member]
Debt Instrument, Face Amount		$ 2
Debt Instrument, Term		360 years
Debt Instrument, Interest Rate, Stated Percentage		4.75%
Short-term Debt, Total				2,000,000
Standby Letters of Credit [Member]
Long-term Line of Credit, Total				900,000
Term Loan [Member]
Debt Instrument, Face Amount			$ 15,500,000
Debt Instrument, Term			10 years
Debt Instrument, Interest Rate, Stated Percentage			4.50%
Debt Instrument, Periodic Payment, Total			$ 160,640
Long-term Line of Credit, Total				$ 6,100,000
Maximum [Member]
Current Funded Debt to EBITDA Ratio	2.25
Annual Capital Expenditures	$ 15,000,000
Minimum [Member]
Debt Service Coverage Rate	1.25
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.50%