Note C - Marketable Equity Securities (Details Textual) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0		$ 0		$ 0
Investment Income, Dividend	272,000	$ 243,000	493,000	$ 502,000
Trading Securities Pledged as Collateral	6,835,000		6,835,000		10,358,000
Marketable Securities, Reclassification			0	0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities	27,000	$ 297,000	27,000	$ 532,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	6,290,000		6,290,000		7,476,000
Available-for-Sale Securities Net Unrealized Holding Gain (Loss), Net of Tax			1,186,000		2,166,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,147,000		2,147,000		1,340,000
Available-for-sale Equity Securities, Gross Unrealized Loss			146,000		109,000
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 6,290,000		$ 6,290,000		$ 7,476,000