v3.4.0.3
LONG-TERM DEBT - Additional Information (Details) - USD ($)
$ in Thousands
 1 Months Ended 2 Months Ended 3 Months Ended
Apr. 01, 2016
Feb. 27, 2015
Oct. 31, 2015
Mar. 31, 2015
Feb. 28, 2015
Mar. 31, 2016
Mar. 31, 2015
Dec. 31, 2015
Nov. 15, 2013
Long-Term Debt                  
Cash payment for contributed assets   $ 99,500         $ 99,500    
Payment for redemption of IDR units   63,000              
Repayment of credit facility   15,000              
Interest expense           $ 3,001 3,473    
Deferred loan costs           2,885   $ 3,261  
Long-term debt           231,550   231,735  
Amount of debt that will become due and payable if the Partnership remains out of compliance with all of the restrictive covenants under the Credit Agreement           231,600      
Amortization of deferred financing costs           376 $ 423    
Azure Credit Agreement                  
Long-Term Debt                  
Interest expense         $ 2,300        
Weighted average interest rate         6.50%        
Allocated weighted average long-term debt         $ 192,000        
Amortization of deferred financing costs         $ 300        
Credit Agreement                  
Long-Term Debt                  
Long-term debt           231,600      
Subsequent Event | Settlement Agreement with AES and NuDevco                  
Long-Term Debt                  
Proceeds from issuance of letter of credit, used to pay down debt under Credit Agreement $ 15,000                
Amount of debt that will become due and payable if the Partnership remains out of compliance with all of the restrictive covenants under the Credit Agreement $ 216,600                
ETG System | Azure Credit Agreement                  
Long-Term Debt                  
Interest expense       $ 400          
Allocated weighted average long-term debt       55,100          
Amortization of deferred financing costs       100          
Revolving Credit Facility                  
Long-Term Debt                  
Financing costs expense   3,200              
Revolving Credit Facility | Credit Agreement                  
Long-Term Debt                  
Amount outstanding   180,800              
Interest expense       $ 600   2,600      
Maximum borrowing capacity   $ 250,000              
Deferred loan costs           $ 2,900   $ 3,300  
Revolving Credit Facility | Credit Agreement, Second Amendment                  
Long-Term Debt                  
Financing costs expense     $ 700            
Maximum borrowing capacity     $ 238,000            
Revolving Credit Facility | Azure | Azure Credit Agreement                  
Long-Term Debt                  
Long-term debt                 $ 50,000
Revolving Credit Facility | LIBOR | Minimum | Credit Agreement                  
Long-Term Debt                  
Debt instrument, basis spread on variable rate   3.25%              
Revolving Credit Facility | LIBOR | Maximum | Credit Agreement                  
Long-Term Debt                  
Debt instrument, basis spread on variable rate   4.25%              
Revolving Credit Facility | Base Rate | Minimum | Credit Agreement                  
Long-Term Debt                  
Debt instrument, basis spread on variable rate   2.25%              
Revolving Credit Facility | Base Rate | Maximum | Credit Agreement                  
Long-Term Debt                  
Debt instrument, basis spread on variable rate   3.25%              
Term Loan | Azure | Azure Credit Agreement                  
Long-Term Debt                  
Long-term debt                 $ 550,000