Note 3 - Net Loss Per Share - Common Shares Excluded from Calculation of Diluted Net (Loss) Income Per Share (Details) - shares shares in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive securities (in shares)		6,830	4,513	6,834	5,015
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)		5,979	2,775	5,983	3,277
Contingent Consideration Liability [Member]
Antidilutive securities (in shares)	[1]	851	1,738	851	1,738

[1] Calculated as follows: (a) the contingent consideration liability balance divided by (b) the closing stock price of our common stock.