Inventories (Tables)
 3 Months Ended
Mar. 31, 2015
Inventory Disclosure [Abstract]  
Inventories
Inventories consist of the following: 
 
 
March 31,
 
December 31,
 
 
2015
 
2014
 
 
(In thousands)
Coal
 
$
117,180

 
$
71,901

Repair parts and supplies
 
122,933

 
118,352

 
 
$
240,113

 
$
190,253