Note 5 - Marketable Securities (Details Textual) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 06, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Dec. 30, 2017	Jun. 30, 2016	Jun. 29, 2016
Marketable Securities			$ 4,594,000	$ 3,632,000		$ 4,594,000
Available-for-sale Securities, Amortized Cost Basis			4,331,000	3,312,000		4,331,000
Available-for-sale Securities, Gross Unrealized Gain				323,000		279,000
Available-for-sale Securities, Gross Unrealized Loss				3,200		16,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value				454,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss				$ 3,200
Available-for-sale Securities, Number of Shares				1,900,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net				$ 1,559,972	$ 1,502,239
Proceeds from Dividends Received	$ 1,200,000
Insignia [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.70
Insignia [Member]
Available-for-sale Securities, Amortized Cost Basis		$ 1,724,000	2,463,000			$ 2,463,000		$ 3,604,000	$ 5,106,000
Available-for-sale Securities, Ownership Percentage				16.00%
Available-for-sale Securities, Acquired During Period, Amortized Cost Basis		32,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		$ 3,414,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities			$ 112,000
Oxbridge [Member]
Available-for-sale Securities, Amortized Cost Basis				$ 727,000			$ 1,516,000
Available-for-sale Securities, Number of Shares				338,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities				$ 789,000