Note 10 - Stockholders' Equity - Common Stock Issuances (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Total no. of shares (in shares)		146,030		7,490,008		110,629
Grant date fair value recorded at issuance		$ 372	[1],[2],[3]	$ 19,360	[4]	$ 686	[5]
Four Board Members [Member] | January, April, July and October 2018 [Member]
Total no. of shares (in shares)		72,157
Grant date fair value recorded at issuance		$ 175
Four Board Members [Member] | January and July 2018 [Member]
Grant date fair value recorded at issuance	[6]	$ 183
Three Employees [Member] | January and July 2018 [Member]
Total no. of shares (in shares)		68,118
James McKenzie, Related Party [Member] | July and December, 2018 [Member]
Total no. of shares (in shares)		5,755
Grant date fair value recorded at issuance	[1]	$ 14
James McKenzie, Related Party [Member] | January, April, August and October 2017 [Member]
Total no. of shares (in shares)				49,980
Grant date fair value recorded at issuance	[7]			$ 200
James McKenzie, Related Party [Member] | January and July 2016 [Member]
Total no. of shares (in shares)						56,782
Grant date fair value recorded at issuance						$ 381
James McKenzie, Related Party [Member] | January, March, September, and December 2016 [Member]
Total no. of shares (in shares)						6,275
Grant date fair value recorded at issuance						$ 38
Three Employee [Member] | January, February and June 2017 [Member]
Total no. of shares (in shares)				28,634
Grant date fair value recorded at issuance	[7]			$ 182
Three Employee [Member] | February and April 2016 [Member]
Total no. of shares (in shares)						718
Grant date fair value recorded at issuance	[8]
Consultants [Member] | January and December 2017 [Member]
Total no. of shares (in shares)				3,293
Grant date fair value recorded at issuance	[9]			$ 16
Two Employees [Member] | January and February 2017 [Member]
Total no. of shares (in shares)				245
Grant date fair value recorded at issuance	[8]
Various Third-party Shareholders [Member] | May 2017 [Member]
Total no. of shares (in shares)				15,000
Grant date fair value recorded at issuance				$ 57
Five Board [Member] | October 2017 [Member]
Total no. of shares (in shares)						7,392,856
Grant date fair value recorded at issuance	[10]					$ 18,905
Four Employee [Member] | January, April, July, and October 2016 [Member]
Total no. of shares (in shares)						46,854
Grant date fair value recorded at issuance	[11]					$ 267

[1] Excludes $24 thousand of stock compensation for stock issued in 2017 that was amortized from prepaid expense in 2018.

[2] The second phase of a 2014 consulting agreement could result in up to an additional 150,000 shares of common stock being granted subject to sales related performance criteria being achieved. At December 31, 2018, those criteria have not been achieved and no shares have been granted for the second phase of the agreement.

[3] Total excludes $3 thousand of stock compensation related to royalties that were recorded as expense but not issued and outstanding as of December 31, 2018.

[4] Does not include stock expense of $170 thousand included in accrued liabilities at December 31, 2017 for unissued stock.

[5] Does not include stock expense of $176 thousand included in accrued liabilities at December 31, 2016.

[6] Includes bonus and royalty of $170 thousand that was accrued and expensed in 2017.

[7] Includes bonuses and royalty of $176 thousand that were accrued and expensed in 2016.

[8] The Company received $0 for the issuance in the cashless option exercises.

[9] Amount includes $24 thousand that was included in prepaid expense at December 31, 2017.

[10] Includes $38 thousand of stock-based expense related to 2015 director fees accrued and expensed in the fourth quarter of 2015.

[11] Bonuses of $366 thousand were accrued and expensed in the fourth quarter of 2015.