Note 11 - Stock-based Compensation - Stock Option Award Activity (Details) - $ / shares		9 Months Ended	12 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Options outstanding (in shares)		1,561
Options outstanding, weighted average exercise price (in dollars per share)	[1]	$ 928.79
Options outstanding, weighted average remaining contractual term (Year)		5 years 302 days	6 years 204 days
Granted (in shares)
Granted, weighted average exercise price (in dollars per share)	[1]
Canceled or forfeited (in shares)		(9)
Canceled or forfeited, weighted average exercise price (in dollars per share)	[1]	$ 72,891.04
Exercised (in shares)
Exercised, weighted average exercise price (in dollars per share)	[1]
Options outstanding (in shares)		1,552	1,561
Options outstanding, weighted average exercise price (in dollars per share)	[1]	$ 556.13	$ 928.79
Options exercisable (in shares)		1,552
Options exercisable, weighted average exercise price (in dollars per share)	[1]	$ 556.13
Options exercisable, weighted average remaining contractual term (Year)		5 years 302 days
Options vested and expected to vest (in shares)		1,552
Options vested and expected to vest, weighted average exercise price (in dollars per share)	[1]	$ 556.13
Options vested and expected to vest, weighted average remaining contractual term (Year)		5 years 302 days

[1] Exercise price of options outstanding range from $20.00 to $99,300.00 as of September 30, 2020.