Note 7 - Indebtedness - Interest Expense on the Notes (Details) - The Notes [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Coupon interest expense at 1.375%	$ 593	$ 593	$ 1,186	$ 1,186
Amortization of debt issuance costs	231	227	461	452
Total interest and amortization of debt issuance costs	$ 824	$ 820	$ 1,647	$ 1,638

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

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