Note 3 - Investments in Securities (Details Textual) - USD ($)				3 Months Ended	9 Months Ended	12 Months Ended
	Jan. 16, 2018	Jun. 30, 2017	Jan. 06, 2017	Jun. 30, 2016	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 30, 2017
Marketable Securities, Total						$ 7,861,000	$ 4,594,000
Available-for-sale Securities, Amortized Cost Basis, Total						6,463,000	4,331,000
Available-for-sale Securities, Gross Unrealized Gain, Total						1,467,000	279,000
Available-for-sale Securities, Gross Unrealized Loss, Total						69,000	16,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value						1,063,000	441,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss						69,000	16,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value						0	0
Marketable Securities, Realized Gain (Loss), Excluding Other than Temporary Impairments, Total						93,066	576,162
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Total						$ 1,559,972	$ 2,755,318
Insignia [Member]
Available-for-sale Securities, Amortized Cost Basis, Total		$ 1,724,000
Common Stock, Dividends, Per Share, Declared			$ 0.70
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Total		$ 771,000
Insignia [Member]
Available-for-sale Securities, Number of Shares							1,650,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Total				$ 1,502,000			$ 2,643,000
Equity Security, Number of Shares Purchased During Period	1,133,000
Equity Method Investment, Ownership Percentage	26.00%					28.00%
Oxbridge [Member]
Available-for-sale Securities, Amortized Cost Basis, Total					$ 727,000			$ 1,516,000
Available-for-sale Securities, Number of Shares						456,206
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Total					$ 789,000