Note 10 - Segment Reporting - Segment Activity (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017		Jan. 01, 2018	Dec. 31, 2017
Revenues from external customers	$ 24,744		$ 21,796	$ 69,837		$ 62,141
Depreciation and amortization	742	[1]	705	2,245	[1]	2,132	[2]
Interest expense	132		137	370		374
Profit (loss) from operations	(1,484)		(2,019)	(9,432)		(7,679)
Segment assets	78,957		79,577	78,957		79,577		$ 86,329	$ 87,909
Other intangible assets, net	14,397		15,852	14,397		15,852			15,568
Goodwill	16,243		20,737	16,243		20,737			17,641
Expenditures for long-lived assets	156	[3]	271	992	[3]	1,083	[3]
Power and Electromechanical Segment [Member]
Revenues from external customers	19,589		16,700	56,929		48,542
Depreciation and amortization	360	[1]	363	1,100	[1]	1,139	[2]
Interest expense	59		75	165		187
Profit (loss) from operations	1,851		890	3,822		1,984
Segment assets	49,260		49,377	49,260		49,377
Other intangible assets, net	8,689		8,979	8,689		8,979
Goodwill	13,089		13,092	13,089		13,092			13,092
Expenditures for long-lived assets	139	[3]	157	808	[3]	786	[3]
Energy Segment [Member]
Revenues from external customers	5,155		5,096	12,908		13,599
Depreciation and amortization	382	[1]	342	1,145	[1]	993	[2]
Interest expense	7		1	13		3
Profit (loss) from operations	(2,162)		(1,660)	(9,586)		(5,924)
Segment assets	25,999		29,495	25,999		29,495
Other intangible assets, net	5,708		6,873	5,708		6,873
Goodwill	3,154		7,645	3,154		7,645			$ 4,549
Expenditures for long-lived assets	17	[3]	114	184	[3]	297	[3]
Corporate and Other [Member]
Revenues from external customers
Depreciation and amortization		[1]			[1]		[2]
Interest expense	66		61	192		184
Profit (loss) from operations	(1,173)		(1,249)	(3,668)		(3,739)
Segment assets	3,698		705	3,698		705
Other intangible assets, net
Goodwill
Expenditures for long-lived assets		[3]			[3]		[3]

[1] For the Power and Electromechanical segment, for the three and nine months ended September 30, 2018, depreciation and amortization includes $207 thousand and $627 thousand, respectively, classified as cost of revenues in the Condensed Consolidated Statements of Operations.

[2] For the Power and Electromechanical segment, depreciation and amortization totals for the three and nine months ended September 30, 2017, include $184 thousand and $496 thousand, respectively, classified as cost of revenues in the Condensed Consolidated Statements of Operations.

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