Note 3 - Income Taxes (Details Textual)					1 Months Ended	3 Months Ended		9 Months Ended			12 Months Ended
	Dec. 22, 2017	May 02, 2017 USD ($)	Jul. 18, 2016 USD ($)	Nov. 24, 2015 USD ($)	May 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 21, 2017	Dec. 31, 2016 USD ($)	Mar. 31, 2018	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%								35.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability								$ 119,000
Income Tax Expense (Benefit)						$ (60,000)	$ 149,000	$ 595,000		$ 152,000
Effective Income Tax Rate Reconciliation, Percent								37.45%		(2.99%)
Estimated Future Liquidation Loss on Tax Attributes						2,900,000		$ 2,900,000
Deferred Tax Assets, Valuation Allowance				$ 11,661,000		11,125,000	12,352,000	11,125,000		$ 12,352,000
Deferred Income Tax Expense (Benefit)								(102,566)
Business Combination, Bargain Purchase, Gain Recognized, Amount, Net								$ 501,880
Canada, France, and United Kingdom [Member]
Number of Foreign Subsidiaries						3		3
Delphax [Member]
Business Acquisition, Percentage of Voting Interests Acquired				38.00%
Payments to Acquire Businesses, Gross				$ 1,050,000
Delphax [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards													$ 6,300,000
Delphax [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards													13,200,000
Delphax [Member] | Alternative Minimum Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount						$ 311,000		$ 311,000
Delphax [Member] | Alternative Minimum Tax Credit Carryforward [Member] | Domestic Tax Authority [Member]
Tax Credit Carryforward, Amount													311,000
Delphax [Member] | Research Tax Credit Carryforward [Member] | Domestic Tax Authority [Member]
Tax Credit Carryforward, Amount													$ 4,300,000
Delphax Canada [Member] | Foreign Tax Authority [Member]
Tax Credit Carryforward, Amount												$ 4,300,000
Operating Loss Carryforwards												$ 4,000,000
Contrail Aviation Support LLC. [Member] | Contrail Aviation Inc. [Member]
Business Combination, Equity Interests in Acquiree, Percentage			21.00%
Business Combination, Equity Interest in Acquiree, Deemed to be Acquired, Percentage			79.00%
Payments to Acquire Businesses, Gross			$ 4,033,367
AirCo [Member] | Acquired Inventory and Principal Business Assets, and Assumed Specified Liabilities, of Aircraft Instrument and Radio Company, Incorporated, and Aircraft Instrument and Radio Services, Inc. [Member]
Payments to Acquire Businesses, Gross		$ 2,400,000			$ 2,400,000
Business Combination, Bargain Purchase, Gain Recognized, Amount		$ 779,880
Deferred Tax Liabilities, Net						$ 278,000		278,000
Deferred Income Tax Expense (Benefit)								278,000
Business Combination, Bargain Purchase, Gain Recognized, Amount, Net								$ 502,000
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent											30.79%