Cash and Cash Equivalents (Tables)
 12 Months Ended
Dec. 31, 2017
CASH AND CASH EQUIVALENTS [Abstract]  
Cash and cash equivalents

 

 

 

 

 

 

 

 

 

 

  

December 31,

2017

 

  

December 31,

2016

 

Cash on hand and at banks

  

$

127,625

 

  

$

126,584

 

Short-term deposits and highly liquid funds

  

 

7

 

  

 

9,408

 

Cash and cash equivalents

  

$

127,632

 

  

$

135,992