Note 15 - Fair Value Measurements and Fair Value of Financial Instruments (Details Textual) - Convertible 2020 Notes [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jun. 20, 2017
Long-term Debt, Fair Value	$ 13,900	$ 12,600	$ 13,500
Embedded Derivative, Fair Value of Embedded Derivative, Net, Total	$ 0

Net fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as assets, net of those classified as liabilities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=117331979&loc=d3e41228-113958

Name:	us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant