Annual report pursuant to Section 13 and 15(d)

- Eastern Interconnect Project (Details)

v3.3.1.900
- Eastern Interconnect Project (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
USD ($)
kV
mi
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Oct. 31, 2012
Eastern Interconnect Project [Member]        
Sale Leaseback Transaction [Line Items]        
Length of transmission lines physical assets | mi 216      
Power of transmission lines physical assets | kV 345      
Estimated useful lives of assets 20 years      
Amount of depreciation of leased property $ 570 $ 2,300 $ 2,300  
Public Service Company of New Mexico [Member]        
Sale Leaseback Transaction [Line Items]        
Business Acquisition, Percentage of Voting Interests Acquired       40.00%
Lease Expiration Date Apr. 01, 2015      
Future Expectations [Member] | Public Service Company of New Mexico [Member]        
Sale Leaseback Transaction [Line Items]        
Fair Value of Lease Option Under Agreement $ 7,700