Note M - Income Taxes - Federal Net Operating Loss Carryforward and Research Activities Credit (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Net Operating Loss Carryforwards $ 103,364    
Research Activities Credit 3,166 $ 2,254 $ 1,793
Tax Year 2007 [Member]      
Net Operating Loss Carryforwards 454    
Research Activities Credit $ 30    
Expiration 2027    
Tax Year 2008 [Member]      
Net Operating Loss Carryforwards $ 1,178    
Research Activities Credit $ 65    
Expiration 2028    
Tax Year 2009 [Member]      
Net Operating Loss Carryforwards $ 3,060    
Research Activities Credit $ 176    
Expiration 2029    
Tax Year 2010 [Member]      
Net Operating Loss Carryforwards $ 3,423    
Research Activities Credit $ 149    
Expiration 2030    
Tax Year 2011 [Member]      
Net Operating Loss Carryforwards $ 9,929    
Research Activities Credit $ 176    
Expiration 2031    
Tax Year 2012 [Member]      
Net Operating Loss Carryforwards    
Research Activities Credit $ 170    
Expiration 2032    
Tax Year 2013 [Member]      
Net Operating Loss Carryforwards $ 4,353    
Research Activities Credit $ 133    
Expiration 2033    
Tax Year 2014 [Member]      
Net Operating Loss Carryforwards $ 15,819    
Research Activities Credit $ 894    
Expiration 2034    
Tax Year 2015 [Member]      
Net Operating Loss Carryforwards $ 24,189    
Research Activities Credit $ 461    
Expiration 2035    
Tax Year 2016 [Member]      
Net Operating Loss Carryforwards $ 40,959    
Research Activities Credit $ 912    
Expiration 2036