Note 15 - Stock-based Compensation - RSU Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Beginning of period, Restricted stock units, Unvested, weighted average grant date fair value (in dollars per share)	$ 0.20
End of period, Restricted stock units, Unvested, weighted average grant date fair value (in dollars per share)		$ 0.20
Restricted Stock Units (RSUs) [Member]
Beginning of period, Restricted stock units, Unvested (in shares)	2,997,399	443,927	382,098
Beginning of period, Restricted stock units, Unvested, weighted average grant date fair value (in dollars per share)	$ 1.41	$ 23.88	$ 20.24
Restricted stock units, Granted (in shares)	3,133,753	3,112,382	192,987
Restricted stock units, Granted, weighted average grant date fair value (in dollars per share)	$ 2.77	$ 0.67	$ 31.42
Restricted stock units, Vested (in shares)	(1,891,869)	(313,508)	(85,153)
Restricted stock units, Vested, weighted average grant date fair value (in dollars per share)	$ 1.63	$ 19.38	$ 25.98
Restricted stock units, Forfeited (in shares)	(400,253)	(245,402)	(46,005)
Restricted stock units, Forfeited, weighted average grant date fair value (in dollars per share)	$ 1.86	$ 6.54	$ 21.38
End of period, Restricted stock units, Unvested (in shares)	3,839,030	2,997,399	443,927
End of period, Restricted stock units, Unvested, weighted average grant date fair value (in dollars per share)	$ 2.36	$ 1.41	$ 23.88