Note 11 - Stock-based Compensation - Stock Option Award Activity (Details) - $ / shares		3 Months Ended	12 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Options outstanding (in shares)		1,552
Options outstanding, weighted average exercise price (in dollars per share)	[1]	$ 556.13
Options outstanding, weighted average remaining contractual term (Year)		5 years 131 days	5 years 211 days
Granted (in shares)
Granted, weighted average exercise price (in dollars per share)	[1]
Canceled or forfeited (in shares)		(35)
Canceled or forfeited, weighted average exercise price (in dollars per share)	[1]	$ 876
Exercised (in shares)
Exercised, weighted average exercise price (in dollars per share)	[1]
Options outstanding (in shares)		1,517	1,552
Options outstanding, weighted average exercise price (in dollars per share)	[1]	$ 548.75	$ 556.13
Options exercisable (in shares)		1,517
Options exercisable, weighted average exercise price (in dollars per share)	[1]	$ 548.75
Options exercisable, weighted average remaining contractual term (Year)		5 years 131 days
Options vested and expected to vest (in shares)		1,517
Options vested and expected to vest, weighted average exercise price (in dollars per share)	[1]	$ 548.75
Options vested and expected to vest, weighted average remaining contractual term (Year)		5 years 131 days

[1] Exercise price of options outstanding range from $20 to $99,300 as of March 31, 2021.