CONCENTRATIONS OF RISK (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Counterparty A | Revenue | Customer concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage 22.00% 28.00%  
Counterparty A | Accounts receivable | Credit concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage 44.00% 38.00%  
Counterparty B | Revenue | Customer concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage 18.00% 20.00% 34.00%
Counterparty B | Accounts receivable | Credit concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage 13.00% 24.00%  
Counterparty C | Revenue | Customer concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage   12.00% 17.00%
Counterparty C | Accounts receivable | Credit concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage 0.00%    
Counterparty D | Revenue | Customer concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage     12.00%
Counterparty E | Revenue | Customer concentration
     
CONCENTRATIONS OF RISK      
Total revenues, major customer percentage     10.00%