Regulatory and Rate Matters (Details) (USD $)										3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended		0 Months Ended			6 Months Ended	12 Months Ended		0 Months Ended	1 Months Ended				0 Months Ended		1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Maximum [Member]	Sep. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Maximum [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Wind Energy [Member] Minimum [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Solar Energy [Member] Minimum [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Renewable Technologies [Member] Minimum [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Distributed Generation [Member] Minimum [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2011 [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2015 [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2020 [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] 2014 Wind generated Renewable Energy Credits [Member] MWh	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Portfolio Standard 2014 [Member] MW	Sep. 30, 2014 Public Service Company of New Mexico [Member] 2015 Wind generated Renewable Energy Credits [Member] MWh	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Portfolio Standard 2015 [Member] MW	Sep. 30, 2014 Public Service Company of New Mexico [Member] Renewable Energy Rider [Member] Maximum [Member]	Oct. 05, 2012 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Disincentives / Incentives Adder [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Disincentives / Incentives Adder [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] 2010 Electric Rate Case [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] 2010 Electric Rate Case [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] FPPAC Continuation Application [Member]	Jul. 31, 2011 Public Service Company of New Mexico [Member] Integrated Resource Plan, 2011 [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Integrated Resource Plan, 2011 [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] La Luz Generating Station [Member] MW	May 02, 2014 Public Service Company of New Mexico [Member] Formula Transmission Rate Case [Member]	Jun. 03, 2013 Public Service Company of New Mexico [Member] Formula Transmission Rate Case [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Formula Transmission Rate Case [Member]	Jun. 30, 2014 Public Service Company of New Mexico [Member] City of Gallup, New Mexico Contract [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] City of Gallup, New Mexico Contract [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Delta [Member] Applications for Approvals to Purchase Delta [Member] MW	Oct. 06, 2014 Public Service Company of New Mexico [Member] Subsequent Event [Member] 2010 Energy Efficiency Application [Member] Disincentives / Incentives Adder [Member]	Jul. 30, 2011 Texas-New Mexico Power Company [Member] Advanced Meter System Deployment and Surcharge Request [Member]	Sep. 30, 2014 Texas-New Mexico Power Company [Member] Advanced Meter System Deployment and Surcharge Request [Member] customer	Sep. 30, 2014 Texas-New Mexico Power Company [Member] Advanced Meter System Deployment and Surcharge Request [Member] Minimum [Member]	Sep. 30, 2014 Texas-New Mexico Power Company [Member] Advanced Meter System Deployment and Surcharge Request [Member] Maximum [Member]	Aug. 28, 2012 Texas-New Mexico Power Company [Member] Energy Efficiency [Member]	Sep. 30, 2014 Texas-New Mexico Power Company [Member] Energy Efficiency [Member]	Jan. 31, 2013 Texas-New Mexico Power Company [Member] Transmission Rate Filings [Member]	Sep. 30, 2014 Texas-New Mexico Power Company [Member] August 2013 Transmission Rate Filings [Member]	Sep. 30, 2014 Texas-New Mexico Power Company [Member] January 2014 Transmission Rate Filings [Member]	Sep. 30, 2014 Texas-New Mexico Power Company [Member] July 2014 Transmission Rate Filings [Member]
Rate Matters [Line Items]
Public Utilities, Required Percentage of Renewable Energy in Portfolio to Electric Sales							10.00%	15.00%	20.00%
Public Utilities, Required Percentage of Diversification			30.00%	20.00%	5.00%	1.50%
Public Utilities, Reasonable Cost Threshold	3.00%	3.00%
Public Utilities, Number of Mega Watt Hours of Wind Generation										50,000		120,000
Public Utilities, Number of Mega Watts of Solar PV Capacity											23		40
Public Utilities, Estimated Cost of Mega Watts of Solar PV Capacity											$ 46,700,000		$ 79,300,000
Public Utilities, Wind Capacity Planned Purchase Agreement Term											20 years
Public Utilities, Number of Mega Watts of Wind Energy Capacity											102
Public Utilities, First Year Cost of Wind Capacity Planned Purchase Agreement											5,800,000.0
Public Utilities, Rider Condition of Earned Return on Jurisdictional Equity in 2013														10.50%
Public Utilities, Annual Revenue To be Collected Under Current Rider Rate														34,600,000
Public Utilities, Annual Revenue To be Collected Under 2015 Rider Rate														44,700,000
Public Utilities, Program Costs Related To Energy Efficiency															22,500,000														25,800,000
Public Utilities, Approved Profit Incentive Adder Revenues Related To Energy Efficiency Program, Percentage of Program Costs																7.60%
Public Utilities, Approved Profit Incentive Adder Revenues Related To Energy Efficiency Program																1,700,000
Public Utilities, Proposed Profit Incentive Adder Revenues Related To 2015 Energy Efficiency Program																													2,100,000
Public Utilities, Retention Percentage of Sales Margins																	10.00%	10.00%
Public Utilities, Under-collected balance write-off																			10,500,000
Public Utilities, Period over which to write off remaining uncollected balance																			18 months
Public Utilities, Frequency of IRP filings																					3 years
Public Utilities, Planning Period Covered of IRP																				20 years
Public Utilities, Number of Mega Watts Natural Gas Peaking Units to be Purchased																												132
Public Utilities, Number of Mega Watts of Gas-fired Generation																						40
Public Utilities, Rate Base Value																						56,000,000
Amount of Regulatory Costs Not yet Approved																									3,200,000
Public Utilities, Return on Equity																									10.81%
Percentage ownership of EIP transmission line																									60.00%
Public Utilities, Requested Rate Increase (Decrease), Amount																							500,000	1,300,000
Public Utilities, Revenue For Power Sold Under Specific Contract																										6,100,000	11,700,000
Public Utilities, Approved Deployment Costs																														113,300,000
Public Utilities, Collection of Deployment Costs Through Surcharge Period																														12 years
Public Utilities, Completion Period of Advanced Meter Deployment																														5 years
Public Utilities, Non-standard metering service cost total to be borne by opt-out customers																															200,000
Public Utilities, Non-standard metering service cost initial fee range																																142.84	247.48
Public Utilities, Non-standard metering ongoing expenses total to be borne by opt-out customers																															500,000
Public Utilities, Non-standard metering ongoing expenses monthly charge																															38.99
Public Utilities, Approved Non-standard metering service cost initial fee range																																63.97	168.61
Public Utilities, Approved Non-standard metering ongoing expenses monthly charge																															36.78
Presumed number of customers that will elect non-standard meter service																															1,081
Current number of customers that have elected non-standard meter service																															59
Public Utilities, Approved Program Implementation Costs, Bonus																																		5,200,000
Public Utilities, Unapproved 2014 Program Implementation Costs																																			5,600,000
Public Utilities, Unapproved 2015 Program Implementation Costs																																			5,700,000
Public Utilities, Approved 2014 Incentive Portion of Program Implementation Costs																																			1,500,000
Public Utilities, Approved 2015 Program Implementation Costs																																			5,700,000
Public Utilities, Additional Revenue from Proposed Rates																																				21,900,000	18,100,000	18,200,000	25,200,000
Public Utilities, Total Revenue Requirement Increase																																				$ 2,900,000	$ 2,800,000	$ 2,900,000	$ 4,200,000