Note 12 - Net Loss Per Share Available to Common Stockholders - Potential Common Shares Outstanding (Details) - shares shares in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Potential common shares outstanding (in shares)	1,284	1,033
Options to Purchase Common Stock [Member]
Potential common shares outstanding (in shares)	430	502
Restricted Stock Units (RSUs) [Member]
Potential common shares outstanding (in shares)	854	531

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration