XML 74 R53.htm IDEA: XBRL DOCUMENT v3.7.0.1
Commitments and Contingencies - Coal Supply (Details)
 3 Months Ended 6 Months Ended 12 Months Ended
Feb. 01, 2016
USD ($)
Jan. 31, 2016
USD ($)
Mar. 31, 2017
USD ($)
Mar. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
May 02, 2017
USD ($)
May 01, 2017
USD ($)
Apr. 24, 2017
USD ($)
Feb. 01, 2017
Aug. 01, 2016
payment
Public Utilities, Commitments And Contingencies [Line Items]                        
Other current assets     $ 66,093,000   $ 73,444,000 $ 73,444,000            
Regulatory disallowances and restructuring costs     0 $ 774,000                
Public Service Company of New Mexico                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Other current assets     60,425,000   67,355,000 67,355,000            
Regulatory disallowances and restructuring costs     0 $ 774,000                
Public Service Company of New Mexico | Increase in coal mine decommissioning liability                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Expense reflected in regulatory disallowances and restructuring costs         4,500,000 4,500,000            
Public Service Company of New Mexico | Mine Reclamation Trust                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Required contribution to Reclamation Trust, current fiscal year     6,900,000                  
Anticipated funding to Reclamation Trust, next fiscal year     8,300,000                  
Anticipated funding to Reclamation Trust, third fiscal year     8,700,000                  
Public Service Company of New Mexico | Mine Reclamation Trust | Four Corners                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Required contribution to Reclamation Trust, current fiscal year     2,000,000                  
Anticipated funding to Reclamation Trust, next fiscal year     2,100,000                  
Anticipated funding to Reclamation Trust, third fiscal year     2,100,000                  
Number of annual installment payments | payment                       13
Public Service Company of New Mexico | Surface                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Regulatory assets     100,000,000                  
Public Service Company of New Mexico | Loss on long-term purchase commitment | Surface                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Loss contingency accrual     41,500,000   41,000,000 41,000,000            
Final reclamation, capped amount to be collected     100,000,000.0                  
Public Service Company of New Mexico | Loss on long-term purchase commitment | Underground                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Loss contingency accrual     14,000,000   14,000,000 14,000,000            
Public Service Company of New Mexico | San Juan Generating Station | Loss on long-term purchase commitment | Surface                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Regulatory disallowances and restructuring costs             $ 16,500,000          
Estimate of possible loss     102,000,000                  
Public Service Company of New Mexico | San Juan Generating Station | Loss on long-term purchase commitment | Underground                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Estimate of possible loss     127,800,000                  
Public Service Company of New Mexico | San Juan Generating Station | Coal supply                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Other current assets     43,000,000   $ 48,700,000 $ 48,700,000            
Estimated increase in coal cost         48.00% 48.00%            
NM Capital | BTMU Term Loan Agreement                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Term loans $ 125,000,000.0   82,800,000                  
NM Capital | San Juan Generating Station | Coal supply                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Payments to fund long-term loans to unaffiliated third party   $ 125,000,000.0                    
Loan agreement among several entities   $ 125,000,000                    
Interest rate   7.25%                 9.25%  
Requirement to post reclamation bonds     118,700,000                  
Cash used to support bank letter or credit arrangement   $ 30,300,000 30,300,000                  
NM Capital | San Juan Coal Company, Westmoreland | Coal supply                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Payments to fund long-term loans to unaffiliated third party $ 125,000,000.0                      
Loan receivable   $ 125,000,000 85,400,000                  
Prepayment penalty     $ 0                  
NM Capital | San Juan Coal Company, Westmoreland | Coal supply | Subsequent event                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Scheduled principal payment proceeds               $ 9,600,000 $ 9,600,000      
Scheduled interest payment proceeds               $ 2,200,000 $ 2,200,000      
Unaffiliated third party | San Juan Coal Company, Westmoreland | Coal supply | Subsequent event                        
Public Utilities, Commitments And Contingencies [Line Items]                        
Amount held in a restricted bank account                   $ 11,800,000