Note 2 - Acquisitions and Divestitures - Divestitures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Book value of assets sold	$ 0	$ 0	$ (1,685)
Book value of liabilities sold	0	0	37
Sales price in excess of net liabilities assumed	0	0	0
Total sales price	0	0	(1,648)
Cash sold	0	0	35
Non-cash sales price	0	0	1,603
Amount due remaining on books	0	0	0
Net cash received in divestitures	$ 0	$ 0	$ (10)