XML 78 R51.htm IDEA: XBRL DOCUMENT v3.4.0.3
Commitments and Contingencies - The Clean Air Act (Details)
 3 Months Ended 12 Months Ended 35 Months Ended
Dec. 16, 2015
USD ($)
MWh
MW
Mar. 02, 2015
lb / MMBTU
T
Mar. 31, 2016
USD ($)
MW
Mar. 31, 2015
USD ($)
Dec. 31, 2015
USD ($)
Jan. 31, 2016
USD ($)
Feb. 09, 2016
Jan. 26, 2016
state
Oct. 01, 2015
parts_per_billion
Sep. 30, 2015
parts_per_billion
Aug. 11, 2015
T
Jul. 31, 2015
MW
Dec. 30, 2013
lbsofnox / mmbtu
Aug. 06, 2012
compliance_alternative
Jan. 31, 2010
parts_per_billion
Jul. 31, 2005
T
Dec. 31, 1999
state
Public Utilities, Commitments And Contingencies [Line Items]                                  
Regulatory disallowances and restructuring costs     $ 774,000 $ 215,000                          
Plant in service, held for future use, and to be abandoned     6,676,612,000   $ 6,307,261,000                        
Accumulated depreciation and amortization     $ 2,246,332,000   2,058,772,000                        
Clean Air Act related to Regional Haze [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Number of states to address regional haze (in states) | state                                 50
Potential to emit tons per year of visibility impairing pollution (in tons, more than) | T                               250  
Clean Power Plan [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Period of potential extension to meet environmental targets     2 years                            
Number of states that filed a petition against the Clean Power Plan | state               29                  
Proposed percentage reduction in CO2 emissions, stayed by the USSC             32.00%                    
Period of time currently remaining to submit initial plans to meet environmental targets     6 months                            
Period of time currently remaining to submit initial plans to meet environmental targets, including potential extension     2 years 6 months                            
Public Service Company of New Mexico [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Regulatory disallowances and restructuring costs     $ 774,000 $ 215,000                          
Plant in service, held for future use, and to be abandoned     5,185,298,000   4,833,303,000                        
Accumulated depreciation and amortization     1,744,062,000   $ 1,569,549,000                        
Public Service Company of New Mexico [Member] | San Juan Generating Station Units 2 and 3 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Plant in service, held for future use, and to be abandoned     471,300,000                            
Accumulated depreciation and amortization     197,200,000                            
Net book value     $ 274,100,000                            
Public Service Company of New Mexico [Member] | San Juan Generating Station And Four Corners [Member] | Minimum [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Proposed government standard emission limit (in ozone parts per million) | parts_per_billion                             60    
Public Service Company of New Mexico [Member] | San Juan Generating Station And Four Corners [Member] | Maximum [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Proposed government standard emission limit (in ozone parts per million) | parts_per_billion                             70    
Government standard emission limit (in ozone parts per million) | parts_per_billion                 70 75              
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Estimated costs to remain unrecovered $ 20,000,000                                
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Units 1 and 4 [Member] | Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Total costs for equipment           $ 76,600,000                      
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Units 2 and 3 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Current ownership interest (in megawatts) | MW 418                                
Time period to recover retired units' remaining net book value 20 years       20 years                        
Recovery percentage of estimated undepreciated value at 12/31/17 50.00%   50.00%   50.00%                        
Estimated undepreciated value at 12/31/17         $ 255,300,000                        
Regulatory disallowances and restructuring costs         127,600,000                        
Expense reflected in regulatory disallowances and restructuring costs     $ 800,000                            
Accumulated plant write-off, disallowance     128,200,000                            
Net carrying value of utility plant     145,900,000                            
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Units 2 and 3 [Member] | Increase in coal mine decommissioning liability [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Regulatory disallowances and restructuring costs         $ 165,700,000                        
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Unit 4 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Additional ownership to be obtained (in megawatts) | MW 65                     132          
Estimated rate base value $ 0                                
Coal-fired generation (in megawatts) | MW 197                                
Number of megawatt hours of Renewable Energy Certificates to be acquired and retired (in megawatt hours) | MWh 1                                
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Unit 4 [Member] | Maximum [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Annual cost of Renewable Energy Credits $ 7,000,000                                
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | Palo Verde Nuclear Generating Station Unit 3 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Estimated undepreciated value at 12/31/17 $ 150,000,000                                
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR Hearing Examiner Recommended Denial [Member] | San Juan Generating Station Unit 4 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Additional ownership to be obtained (in megawatts) | MW 132                                
Public Service Company of New Mexico [Member] | Clean Air Act, Post-2022 Coal Supply future rate case [Member] | San Juan Generating Station Unit 4 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Period of time agreed to by all parties to settle rate case 6 months                                
Public Service Company of New Mexico [Member] | Clean Air Act Related to Post Combustion Controls [Member] | Four Corners [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Number of compliance alternatives | compliance_alternative                           2      
Plant requirement to meet NOx emissions limit (in pounds of NOx per MMBTU) | lbsofnox / mmbtu                         0.015        
Plant requirement to meet opacity limit                         20.00%        
Rule imposes opacity limitation on certain fugitive dust emissions from coal and material handling operations                         20.00%        
Loss contingency, estimate of possible loss     $ 91,400,000                            
Public Service Company of New Mexico [Member] | Clean Air Act Related to Post Combustion Controls [Member] | Four Corners Units 4 and 5 (Coal) [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Ownership percentage                         13.00%        
Public Service Company of New Mexico [Member] | National Ambient Air Quality Standards, 2015 EPA Legal Settlement [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Period of time to act on settlement   16 months                              
Emissions tons of SO2 per year | T   16,000                              
Public Service Company of New Mexico [Member] | National Ambient Air Quality Standards, 2015 EPA Legal Settlement [Member] | Minimum [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Emissions tons of SO2 per year | T   2,600                              
Public utilities, 1-hour SO2 emissions rate (in pounds per MMBTU) | lb / MMBTU   0.45                              
Public Service Company of New Mexico [Member] | National Ambient Air Quality Standards, 2015 EPA Legal Settlement [Member] [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Period of time from state designation, to provide implementation plans     36 months                            
Public Service Company of New Mexico [Member] | National Ambient Air Quality Standards, 2015 EPA Legal Settlement [Member] [Member] | Minimum [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Emissions tons of SO2 per year | T                     2,000            
PNMR and PNM [Member] | Palo Verde Nuclear Generating Station Unit 3 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Number of megawatts | MW     134                            
PNMR and PNM [Member] | Clean Air Act, SNCR [Member] | Palo Verde Nuclear Generating Station Unit 3 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Number of megawatts | MW 134                                
PNMR Development [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Unit 4 [Member]                                  
Public Utilities, Commitments And Contingencies [Line Items]                                  
Expense for cost, obligation to reimburse     $ 600,000                            
Potential acquisition of ownership (in megawatts) | MW                       65