Note 12 - Summary of Stock Options - Summary of Option Activity Under All Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Options outstanding (in shares)	40,144	26,903
Options outstanding, weighted average exercise price (in dollars per share)	$ 455.68	$ 579.81
Options outstanding, weighted average remaining contractual term (Year)	9 years 328 days	7 years 146 days	8 years 219 days
Options outstanding, aggregate intrinsic value	$ 3,928,715		$ 249,154
Options granted (in shares)	10,065,844	23,542
Options granted, weighted average exercise price (in dollars per share)	$ 1.14	$ 351.81
Options exercised (in shares)
Options exercised, weighted average exercise price (in dollars per share)
Options canceled (in shares)	(18,310)	(10,301)
Options canceled, weighted average exercise price (in dollars per share)	$ 403.31	$ 548.13
Options outstanding (in shares)	10,087,678	40,144	26,903
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.22	$ 455.68	$ 579.81
Vested and exercisable and expected to vest, end of period (in shares)	8,966,825
Vested and exercisable and expected to vest, end of period, weighted average exercise price (in dollars per share)	$ 2.36
Vested and exercisable and expected to vest, end of period, weighted average remaining contractual term (Year)	9 years 328 days
Vested and exercisable and expected to vest, end of period, aggregate intrinsic value	$ 3,490,722
Vested and exercisable, end of period (in shares)	222,582
Vested and exercisable, end of period, weighted average exercise price (in dollars per share)	$ 41.49
Vested and exercisable, end of period, weighted average remaining contractual term (Year)	9 years 182 days
Vested and exercisable, end of period, aggregate intrinsic value	$ 77,540