Note 12 - Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Amortization of debt issuance costs			$ 650	$ 673
The 5% Convertible Senior Notes Due 2024 [Member]
Contractual interest expense	$ 1,006	$ 1,006	3,018	3,018
Amortization of debt issuance costs	208	209	618	623
Total interest cost	$ 1,214	$ 1,215	$ 3,636	$ 3,641
Effective interest rate	5.10%	5.10%	5.10%	5.10%