Note 5 - Goodwill and Intangible Assets (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 31, 2015
Goodwill, Ending Balance	$ 22,105	$ 22,105
Finite-Lived Intangible Assets, Gross, Total	12,729	12,729
Amortization of Intangible Assets, Total	1,600	1,600	$ 1,600
Operating Rights [Member]
Finite-Lived Intangible Assets, Gross, Total	6,529	6,529		$ 6,500
Natural Habitat, Inc [Member]
Goodwill, Ending Balance	$ 22,100	$ 22,100