Note 10 - Stock-based Compensation - RSU Activity (Details) - Restricted Stock Units (RSUs) [Member]	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Beginning of period, Restricted stock units, Unvested (in shares) | shares	3,839,030
Beginning of period, Restricted stock units, Unvested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 2.36
Restricted stock units, Granted (in shares) | shares	5,133,307
Restricted stock units, Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0.80
Restricted stock units, Vested (in shares) | shares	(1,603,449)
Restricted stock units, Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 2.53
Restricted stock units, Forfeited (in shares) | shares	(69,777)
Restricted stock units, Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.49
End of period, Restricted stock units, Unvested (in shares) | shares	7,299,111
End of period, Restricted stock units, Unvested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 1.24