Note 11 - Long-term Debt - Summary of Long-term Debt (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Long-term debt	$ 55,000,000	$ 55,000,000
Less current portion	0	0
Total long-term debt	$ 55,000,000	55,000,000
Line of Credit [Member]
Long-term debt, weighted average interest rate	3.80%
Long-term debt, maturities	2020
Long-term debt	$ 55,000,000	$ 55,000,000