Note 4 - Fair Value Measurements - Activity for Items Measured at Fair Value on a Recurring Basis (Details) - Stock Purchase Warrants [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Balance	$ 1,694	$ 3,620	$ 2,651	$ 1,830
Initial fair value at the original issuance date	0	21,914	1,110	23,746
Equity classified warrant put feature activated	0	51	0	51
Change in fair value during the period	(1,225)	(5,133)	(2,018)	(5,175)
Fair value of warrants exercised	0	0	(1,274)	0
Seneca liability classified warrants assumed	0	200	0	200
Expiration of equity classified warrant put feature	0	(27)	0	(27)
Settlement of liability - classified warrants	0	(99)	0	(99)
Balance	$ 469	$ 20,526	$ 469	$ 20,526