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		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive securities (in shares)		7,076	5,588	7,160	5,587
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)		6,298	3,237	6,382	3,236
Contingent Consideration Liability [Member]
Antidilutive securities (in shares)	[1]	778	2,351	778	2,351

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