Note 2 - Summary of Significant Accounting Policies - Summary of Segment Activity (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from external customers		$ 23,492	$ 20,342	$ 18,843
Depreciation and amortization (1)	[1]	2,361	3,005	2,850
Interest expense		61	216	201
Loss from operations		(16,045)	(22,134)	(16,305)
Segment assets		64,158	70,167	87,909
Other intangibles assets, net		4,298	5,353	6,728
Expenditures for segment assets (2)	[2]	674	1,534	1,531
Impairment of goodwill and other intangible assets			4,347	3,152
Goodwill		0	0	4,549
Energy Segment [Member]
Revenues from external customers		23,492	20,342	18,843
Depreciation and amortization (1)	[1]	1,520	1,525	1,345
Interest expense		52	23	1
Loss from operations		(8,615)	(17,168)	(11,366)
Segment assets		21,461	19,034	26,512
Other intangibles assets, net		4,276	5,314	6,669
Expenditures for segment assets (2)	[2]	135	235	576
Impairment of goodwill and other intangible assets			4,347	3,152
Goodwill				4,549
Other Segments [Member]
Revenues from external customers
Depreciation and amortization (1)	[1]	841	1,480	1,505
Interest expense		9	193	200
Loss from operations		(7,430)	(4,966)	(4,939)
Segment assets		42,697	51,133	61,397
Other intangibles assets, net		22	39	59
Expenditures for segment assets (2)	[2]	$ 539	1,299	955
Impairment of goodwill and other intangible assets
Goodwill

[1] For the years ended December 31, 2019, 2018 and 2017, depreciation and amortization totals included $0.8 million, $1.5 million and $1.5 million, respectively that were classified in income from discontinued operations on the Consolidated Statements of Operations.

[2] Includes purchases of property, plant and equipment and investment in other intangible assets.