Note F - Treasury Stock (Details Textual) - USD ($)	6 Months Ended
	Jun. 30, 2017	May 31, 2017	Dec. 31, 2016
Treasury Stock, Value, Acquired, Cost Method	$ 1,193,000
Treasury Stock, Shares	5,183,832		5,114,060
Treasury Stock, Value	$ 124,028,000		$ 122,835,000
September 2011 Reauthorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased		500,000
Treasury Stock, Shares, Acquired	69,772
Treasury Stock, Value, Acquired, Cost Method	$ 1,193,000