Note 6 - Long-term Leases - Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating cash flows for operating leases	$ 35,881
Operating cash flows for finance leases	1,306
Financing cash flows for finance leases	$ 3,923	$ 3,696	$ 3,481