Note 7 - Debt, Credit Facility and Leases - Debt Summary (Details) - Senior Notes [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Principal	$ 513,359	$ 512,886
Unamortized discount/premium and issuance costs	(5,367)	(5,644)
Long-term debt balance	507,992	507,242
The 2028 Senior Notes [Member]
Principal	475,000	475,000
Unamortized discount/premium and issuance costs	(6,234)	(6,462)
Long-term debt balance	468,766	468,538
IQ Notes [Member]
Principal	38,359	37,886
Unamortized discount/premium and issuance costs	867	818
Long-term debt balance	$ 39,226	$ 38,704

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant