Note 12 - Asset Retirement Obligations and Environmental Reserves (Tables)
 12 Months Ended
Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]  
Schedule of Asset Retirement Obligations [Table Text Block]
   

2015

    

2014

  

Beginning balance

   $ 796     $ 771  

Accretion expense

     26       25  

Balance at December 31

   $ 822     $ 796