Cash and Cash Equivalents (Tables)
 12 Months Ended
Dec. 31, 2015
CASH AND CASH EQUIVALENTS [Abstract]  
Cash and cash equivalents
 
 
 
 
 
 
 
 
 
 
  
December 31,
 2015
 
  
December 31,
 2014
 
Cash on hand and at banks
  
$
85,570
  
  
$
157,975
  
Short-term deposits and highly liquid funds
  
 
77,842
  
  
 
89,581
  
Cash and cash equivalents
  
$
163,412
  
  
$
247,556