Note 8 - Long-term Debt and Credit Facility - Long-term Debt (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Long term debt	$ 307,063,000	$ 314,219,000
Less – Current maturities of long-term debt	32,810,000	29,469,000
Less – Unamortized loan costs	2,421,000	2,747,000
Total	271,832,000	282,003,000
Medium-term Notes [Member]
Long term debt	269,063,000	282,188,000
Line of Credit [Member]
Long term debt	38,000,000	31,000,000
Notes Payable, Other Payables [Member]
Long term debt	$ 0	$ 1,031,000