Note 6 - Convertible Senior Notes - Schedule of Long-term Debt (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Unamortized issuance costs	$ (3,263)
Total	3,171,000	$ 571,000
March 2023 Note [Member] | Convertible Senior Notes [Member]
Principal balance	402,500,000
Unamortized issuance costs	(11,008,000)
Carrying value, net	391,492,000
Contractual interest expense	331,000
Amortization of issuance costs	55,000
Total	$ 386,000