Regulatory and Rate Matters - Application for Certificate of Convenience and Necessity (Details) - San Juan Generating Station Units 2 and 3 [Member] - Clean Air Act, SNCR [Member] - Public Service Company of New Mexico [Member] - MW	Apr. 26, 2016	Jun. 30, 2015
Public Utilities, General Disclosures [Line Items]
Newly-identified replacement gas plant (in mw)	80	187
Additional peaking capacity (in mw)	40