XML 50 R36.htm IDEA: XBRL DOCUMENT v3.21.1
Note 9 - Inventories (Tables)
3 Months Ended
Mar. 31, 2021
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
  

March 31,

  

December 31,

 
  

2021

  

2020

 

Coal

 $10,227  $7,163 

Supplies

  44,982   49,037 

Total Inventories

 $55,209  $56,200