Note 11 - Stock-Based Compensation - Stock Option Award Activity (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Options outstanding at December 31, 2017 (in shares) | shares	2,346
Options outstanding at December 31, 2017 (in dollars per share) | $ / shares	$ 2,103.20
Granted (in shares) | shares
Granted (in dollars per share) | $ / shares
Canceled or forfeited (in shares) | shares	(33)
Canceled or forfeited (in dollars per share) | $ / shares	$ 876
Exercised (in shares) | shares
Exercised (in dollars per share) | $ / shares
Options outstanding at December 31, 2018 (in shares) | shares	2,313
Options outstanding at December 31, 2018 (in dollars per share) | $ / shares	$ 2,358.44
Options Outstanding, Weighted- Average Remaining Contractual Life in Years (Year)	6 years 321 days
Options Exercisable, Number of Options (in shares) | shares	1,922
Options Exercisable, Weighted- Average Exercise Price (in dollars per share) | $ / shares	$ 2,517.03
Options Exercisable, Weighted- Average Remaining Contractual Life in Years (Year)	6 years 222 days
Options vested and expected to vest at December 31, 2018 (in shares) | shares	2,313
Options vested and expected to vest at December 31, 2018 (in dollars per share) | $ / shares	$ 2,358.44
Options vested and expected to vest at December 31, 2018 (Year)	6 years 317 days