Note 2 - Long-term Debt - Components of Long-term Debt (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019	Oct. 18, 2018
Debt instrument		$ 632,460	$ 730,000
Total long-term debt		625,286	719,533
Credit Agreement [Member]
Debt instrument	[1]	80,000	105,000
Total long-term debt		80,000	105,000
Senior Second Lien Notes Due November 2023 [Member]
Debt instrument	[1]	545,286	614,533
Principal		552,460	625,000	$ 625,000
Unamortized debt issuance costs		(7,174)	(10,467)
Total long-term debt		$ 545,286	$ 614,533

[1] Defined below