XML 83 R60.htm IDEA: XBRL DOCUMENT v3.19.1
Commitments and Contingencies - Royalty Rates, Tax Assessment, Insurance and Other Matters (Details)
 1 Months Ended 3 Months Ended
Mar. 28, 2017
Sep. 30, 2012
landowner
Apr. 30, 2010
city
Mar. 31, 2019
USD ($)
generating_unit
Dec. 01, 2015
Allotment_Parcel
Jul. 13, 2015
a
Jan. 22, 2015
Allotment_Parcel
Feb. 27, 2014
lawsuit
Aug. 31, 2013
Continuous highwall mining | San Juan Generating Station                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Proposed retroactive surface mining royalty rate                 12.50%
Surface mining royalty rate applied       8.00%          
Estimated underpaid surface mining royalties under proposed rate change       $ 5,000,000          
PNM's share estimated underpaid surface mining royalties under proposed rate change       46.30%          
PNM | Navajo Nation Allottee Matters                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Number of landowners involved in the appeal | landowner   43              
Number of allotments where landowners are revoking rights of way renewal consents (in allotment parcels) | Allotment_Parcel         2   10    
Area of land (in acres) | a           15.49      
Number of allotment parcels at issue that are not to be condemned | Allotment_Parcel         2        
Number of allotment parcels at issue | Allotment_Parcel         5        
PNM | Palo Verde Nuclear Generating Station                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Number of cities to provide cooling water | city     5            
Term of agreement for cooling water     40 years            
PNM | Palo Verde Nuclear Generating Station | Nuclear plant                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Ownership percentage in nuclear reactor       10.20%          
Number of units | generating_unit       3          
Maximum potential assessment per incident       $ 41,600,000.0          
Annual payment limitation related to incident       6,200,000.0          
Aggregate amount of all risk insurance       2,750,000,000.00          
Maximum amount under Nuclear Electric Insurance Limited       5,400,000.0          
PNM | Maximum | Palo Verde Nuclear Generating Station | Nuclear plant                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Liability insurance coverage       14,100,000,000.0          
Liability insurance coverage sublimit       2,250,000,000.00          
Commercial providers | PNM | Palo Verde Nuclear Generating Station | Nuclear plant                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Liability insurance coverage       450,000,000          
Industry Wide Retrospective Assessment Program | PNM | Palo Verde Nuclear Generating Station | Nuclear plant                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Liability insurance coverage       $ 13,600,000,000.0          
Pending litigation                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Number of pending claims | lawsuit               2  
Written notification to terminate agreement, minimum period of time required 30 days                
Settled litigation                  
Public Utilities, Commitments And Contingencies [Line Items]                  
Number of pending claims | lawsuit               1