Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Gain on change in control of interests, net	$ 149,200	$ 107,200
Elmont Plaza [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest	50.00%
Gain on change in control of interests, net	$ (200)
Kimstone [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest	33.30%
Gain on change in control of interests, net	$ 140,000
Montgomery Plaza [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest	20.00%
Gain on change in control of interests, net	$ 6,300
Conroe Marketplace [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest	15.00%
Gain on change in control of interests, net	$ 2,400
District Heights [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest	15.00%
Gain on change in control of interests, net	$ 700
LaSalle Properties [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest		11.00%
Gain on change in control of interests, net		$ 3,700
KIF 1 Portfolio [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest		39.10%
Gain on change in control of interests, net		$ 65,600
SEB Portfolio [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest		15.00%
Gain on change in control of interests, net		$ 14,400
BIG Portfolios [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest		50.10%
Gain on change in control of interests, net		$ 19,500
North Quincy Plaza [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest		11.00%
Gain on change in control of interests, net		$ 2,200
Belmart Plaza [Member]
Note 3 - Property Acquisitions, Developments and Other Investments (Details) - Previous Ownership Interest and Gain on Change of Interest [Line Items]
Previous ownership interest		21.50%
Gain on change in control of interests, net		$ 1,800