Note 2 - Basis of Presentation and Recent Accounting Pronouncements (Details Textual) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Jan. 01, 2019
Fair Value Adjustment of Warrants
Warrant [Member]
Derivative Liability, Total
Accounting Standards Update 2017-11 [Member] | Warrant [Member]
Derivative Liability, Total			$ (2,192)
Fair Value Adjustment of Warrants	$ (275)	(1,267)
Additional Paid-in Capital [Member] | Accounting Standards Update 2017-11 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			6,970
Retained Earnings [Member] | Accounting Standards Update 2017-11 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ (4,778)
Retained Earnings [Member] | Accounting Standards Update 2017-11 [Member] | Warrant [Member]
Fair Value Adjustment of Warrants		$ (1,267)