Note 16 - Dispositions (Details Textual) - USD ($)		3 Months Ended		12 Months Ended
	Jun. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2017
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal				$ (1,160,574)
Certain Assets from Test and Measurement business segment Sold Under an Asset Purchase Agreement to Hickock Waekon, LLC [Member]
Disposal Group, Including Discontinued Operation, Consideration	$ 1,600,000
Disposal Group, Excluding Discontinued Operation, Net Assets Sold	2,700,000
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ (1,200,000)
Certain Assets from Test and Measurement business segment Sold Under an Asset Purchase Agreement to Hickock Waekon, LLC [Member] | Director and His Affiliate [Member] | Common Class A [Member]
Disposal Group, Excluding Discontinued Operation, Consideration, Shares	21,413
Certain Assets from Test and Measurement business segment Sold Under an Asset Purchase Agreement to Hickock Waekon, LLC [Member] | Director and His Affiliate [Member] | Common Class B [Member]
Disposal Group, Excluding Discontinued Operation, Consideration, Shares	176,768