Regulatory and Rate Matters - PNM Solar Direct, Application for a New 345-kV Transmission Line and Wester Spirit Line (Details) $ in Millions	Oct. 02, 2020 USD ($)	May 31, 2019 MW	May 01, 2019 USD ($) kv	Aug. 10, 2018 USD ($) kv
PNM Solar Direct
Public Utilities, General Disclosures [Line Items]
Solar distributed generation (in mw) \| MW		50
PPA term		15 years
KV Transmission Line
Public Utilities, General Disclosures [Line Items]
Transmission line and associated facilities \| kv				345
Estimated cost of project	$ 109			$ 85
Increase (decrease) in estimated cost of project	$ 24
Western Spirit Line
Public Utilities, General Disclosures [Line Items]
Transmission line and associated facilities \| kv			345
Estimated cost of project			$ 285
Estimated self-fund amount under agreement			$ 75