Note 2 - Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Restricted Cash
Restricted Cash	$ 1.4	$ 1.3
Restricted Cash, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherCurrentAssets	us-gaap:OtherCurrentAssets
Inventories
Supply inventory	$ 2.5	$ 2.9