XML 23 R12.htm IDEA: XBRL DOCUMENT v3.20.2
Inventories
6 Months Ended
Jun. 30, 2020
Inventory Disclosure [Abstract]  
Inventories Inventories

Inventories are summarized as follows:
 
JUNE 30
2020
 
DECEMBER 31
2019
Coal
$
8,929

 
$
15,700

Mining supplies
26,803

 
24,765

 Total inventories
$
35,732

 
$
40,465