Note 12 - Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Amortization of debt issuance costs			$ 673	$ 673
The 5% Convertible Senior Notes Due 2024 [Member]
Contractual interest expense	$ 1,006	$ 984	3,018	2,270
Amortization of debt issuance costs	209	207	623	473
Total interest cost	$ 1,215	$ 1,191	$ 3,641	$ 2,743
Effective interest rate	5.10%	5.10%	5.10%	5.10%