Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Other Assets, Total	$ 218,724		$ 218,724	$ 218,724		$ 345,012
Marketable Securities, Total	556,791		556,791	556,791		9,353
Marketable Securities, Gain (Loss), Total	(76,931)	$ (199)		$ 444,646	$ 1,375
Revision of Prior Period, Reclassification, Adjustment [Member]
Other Assets, Total						$ (9,400)
Other Income	$ (200)		$ (1,400)