Regulatory and Rate Matters - Proceeding Regarding Definition of Future Test Year (Details) - 2014 Electric Rate Case [Member] - Public Service Company of New Mexico [Member]	Nov. 30, 2015	Jul. 31, 2015	May 27, 2015
Public Utilities, General Disclosures [Line Items]
Defined future test year as period that begins a period of time following the filing of an application to increase rates (no later than)			45 days
Belief that the correct interpretation of future test year is period time after filing of an application (up to)			13 months
Motion for a temporary stay		30 days
Redefined future test year as period that begins a period of time following the filing of a rate case application (up to)	13 months