Note 1 - Nature of Operations and Basis of Presentation (Details Textual)	3 Months Ended
Mar. 31, 2018
Number of Subsidiaries in Reportable Segments	3
Number of Categories in Product Offerings	2
Power and Electromechanical and Energy Segments [Member]
Number of Reportable Segments	2

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration