Note 11 - Stock-based Compensation - Stock Option Award Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Options outstanding (in shares)	2,313
Granted (in shares)	0	0
Canceled or forfeited (in shares)	(752)
Exercised (in shares)
Options outstanding (in shares)	1,561	2,313
Options exercisable (in shares)	1,511
Options vested and expected to vest (in shares)	1,561
Options outstanding, weighted average exercise price (in dollars per share)	$ 2,358.44
Granted, weighted average exercise price (in dollars per share)
Canceled or forfeited, weighted average exercise price (in dollars per share)	5,151.80
Exercised, weighted average exercise price (in dollars per share)
Options outstanding, weighted average exercise price (in dollars per share)	928.79	$ 2,358.44
Options exercisable, weighted average exercise price (in dollars per share)	1,043.47
Options vested and expected to vest, weighted average exercise price (in dollars per share)	$ 928.79
Options outstanding, weighted average remaining contractual term (Year)	6 years 204 days	6 years 317 days
Options exercisable, weighted average remaining contractual term (Year)	6 years 193 days
Options vested and expected to vest, weighted average remaining contractual term (Year)	6 years 204 days