Note D - Marketable Equity Securities (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Equity Securities, Impairment Loss, Cumulative Amount					$ 2,314,000
Investment Income, Dividend	$ 254,000	$ 272,000	$ 472,000	$ 493,000
Equity Securities, FV-NI, Unrealized Gain (Loss), Total	333,000
Margin Account Borrowings [Member] | Accrued Expenses and Other Liabilities [Member]
Short-term Debt, Total	$ 7,504,000		$ 7,504,000		$ 5,903,000