Regulatory and Rate Matters (Details) (USD $)			1 Months Ended	6 Months Ended																3 Months Ended			3 Months Ended		6 Months Ended	3 Months Ended	0 Months Ended	6 Months Ended				0 Months Ended	3 Months Ended				3 Months Ended			6 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	0 Months Ended					0 Months Ended			1 Months Ended	0 Months Ended		1 Months Ended	3 Months Ended
	Jun. 30, 2013 Public Service Company of New Mexico [Member] Emergency FPPAC [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] La Luz Generating Station [Member] MW	Dec. 31, 2011 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] MW	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Minimum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Maximum [Member]	Mar. 31, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Maximum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Wind Energy [Member] Minimum [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Wind Energy [Member] Minimum [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Solar Energy [Member] Minimum [Member]	Sep. 30, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Solar Energy [Member] Minimum [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Renewable Technologies [Member] Minimum [Member]	Sep. 30, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Renewable Technologies [Member] Minimum [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Distributed Generation [Member] Minimum [Member]	Sep. 30, 2012 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Distributed Generation [Member] Minimum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2011 [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2015 [Member]	Mar. 31, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2015 [Member] Distributed Generation [Member] Minimum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard [Member] Required Percentage by 2020 [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard Supplemental Procurement [Member] MW	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard Supplemental Procurement Reduction [Member] Minimum [Member] MW	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard Supplemental Procurement Reduction [Member] Maximum [Member] MW	Jun. 30, 2013 Public Service Company of New Mexico [Member] 2014 Wind generated Renewable Energy Credits [Member] MWh	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard 2014 [Member] MW	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Portfolio Standard 2014 [Member] MW	Jun. 30, 2013 Public Service Company of New Mexico [Member] 2015 Wind generated Renewable Energy Credits [Member] MWh	Aug. 20, 2011 Public Service Company of New Mexico [Member] NMPRC Rulemaking on Disincentives to Energy Efficiency Programs [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] NMPRC Rulemaking on Disincentives to Energy Efficiency Programs [Member]	Nov. 29, 2010 Public Service Company of New Mexico [Member] NMPRC Rulemaking on Disincentives to Energy Efficiency Programs [Member]	May 03, 2010 Public Service Company of New Mexico [Member] NMPRC Rulemaking on Disincentives to Energy Efficiency Programs [Member] Per KWh [Member] Maximum [Member]	May 03, 2010 Public Service Company of New Mexico [Member] NMPRC Rulemaking on Disincentives to Energy Efficiency Programs [Member] Per kilowatt [Member]	Oct. 05, 2012 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Disincentives / Incentives Adder [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Disincentives / Incentives Adder [Member]	Aug. 11, 2011 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Disincentives / Incentives Adder [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Per KWh [Member] Amended [Member] Minimum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] 2010 Energy Efficiency Application [Member] Per kilowatt [Member] Amended [Member] Minimum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] 2010 Electric Rate Case [Member]	Mar. 31, 2013 Public Service Company of New Mexico [Member] 2010 Electric Rate Case [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Energy Rider [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Energy Rider [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Energy Rider [Member] Maximum [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Renewable Energy Rider [Member] Maximum [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member] Renewable Energy Rider [Member] Maximum [Member]	Jul. 31, 2011 Public Service Company of New Mexico [Member] Integrated Resource Plan, 2011 [Member] Protests_Filed	Jun. 30, 2013 Public Service Company of New Mexico [Member] Integrated Resource Plan, 2011 [Member]	Jul. 03, 2012 Public Service Company of New Mexico [Member] Transmission Rate Case [Member]	Oct. 27, 2010 Public Service Company of New Mexico [Member] Transmission Rate Case [Member]	Jul. 26, 2013 Public Service Company of New Mexico [Member] Formula Transmission Rate Case [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] Formula Transmission Rate Case [Member]	Jan. 02, 2013 Public Service Company of New Mexico [Member] Formula Transmission Rate Case [Member]	Dec. 06, 2012 Public Service Company of New Mexico [Member] Firm Requirements Wholesale Power Rate Case [Member]	Sep. 15, 2011 Public Service Company of New Mexico [Member] Firm Requirements Wholesale Power Rate Case [Member]	Jun. 30, 2013 Public Service Company of New Mexico [Member] City of Gallup, New Mexico Contract [Member]	Jul. 31, 2011 Texas-New Mexico Power Company [Member] Advanced Meter System Deployment and Surcharge Request [Member]	Aug. 28, 2012 Texas-New Mexico Power Company [Member] Energy Efficiency [Member]	Jun. 30, 2013 Texas-New Mexico Power Company [Member] Energy Efficiency [Member]	Jan. 31, 2013 Texas-New Mexico Power Company [Member] Transmission Rate Filings [Member]	Jun. 30, 2013 Texas-New Mexico Power Company [Member] August 2013 Transmission Rate Filings [Member]	Jun. 30, 2013 Delta [Member] Public Service Company of New Mexico [Member] Applications for Approvals to Purchase Delta [Member] MW
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								20.00%	30.00%	20.00%	20.00%	5.00%	10.00%	1.50%	1.50%			3.00%
Public Utilities, Reasonable Cost Threshold					2.00%	3.00%	3.00%
Public Utilities, Annual Incremental Increase in Reasonable Cost Threshold				0.25%
Public Utilites, Additional Renewable Procurements Spending Required by NMPRC			$ 900,000
Public Utilities, Number of Mega Watts of Solar PV Capacity				20																2	1.5	2		23	23
Public Utilities, Number of Mega Watts of Wind Energy Capcity																								100
Public Utilities, First Year Cost of Wind Capacity Planned Purchase Agreement																									5,800,000.0
Public Utilities, Number of Mega Watt Hours of Wind Generation																							50,000			120,000
Public Utilities, Requested Rider Rate For 2014																								0.0044391
Public Utilities, Estimated Cost of Mega Watts of Solar PV Capacity				45,500,000																4,500,000					46,700,000
Public Utilities, Number of Mega Watts of Geothermal Capacity				10
Public Utilities, Wind Capacity Planned Purchase Agreement Term																									20 years
Public Utilities, Program Costs Related To Energy Efficiency																																22,500,000
Public Utilities, Proposed Profit Incentive Adder Revenues Related To Energy Efficiency Program																																4,200,000	2,900,000
Public Utilities, Rate Adder Allowed																														0.01	10				0.002	4
Public Utilities, Rate Rider Recovered																											2,600,000
Public Utilities, Regulatory Costs Approved																													4,200,000																					2,900,000
Percentage ownership of EIP transmission line																																																	60.00%
Public Utilities, Eliminated Recovery of Adder Revenue																																		1,300,000
Public Utilities, Rate Rider Net Over-Recovery																												200,000
Public Utilities, Rate Rider Program Costs Over-Recovery																												1,000,000
Public Utilities, Rate Rider Incentives Under-Recovery																												800,000
Public Utilities, Rate Rider Estimated Incentives Under-Recovery																												500,000
Public Utilities, Regulatory Costs to be Collected																																					36,200,000	38,800,000
Public Utilities, Regulatory Costs Incurred and Eligible For Recovery, Amount Deferred for Collection in Future Period																																					49,600,000
Public Utilities, Additional Revenue To be Collected in 2012																																											18,000,000
Public Utilities, Additional Revenue To be Collected in 2013																																										24,600,000
Public Utilities, Rider Condition of Earned Return on Jurisdictional Equity in 2013																																									10.50%
Public Utilities, Rate Rider to be Implemented																																							0.030468	0.030468
Public Utilities, Approved Rider Rate For 2012																																								0.0022335
Public Utilities, Approved Rider Rate For 2013																																								0.0028371
Public Utilities, Order Disapproved Recovery of Costs As Regulatory Agency Had Not Acted on Specific Procurements Proposed																																							900,000
Public Utilities, Planning Period Covered of IRP																																												20 years
Public Utilities, Number of protests that were filed to IRP requesting rejection of the plan																																												2
Amount of Regulatory Costs Not yet Approved	8,000,000																																														11,100,000	1,300,000	3,200,000			8,700,000
Public Utilites, Number of Mega Watts Natural Gas Peaking Units to be Purchased																																																											132
Public Utilities, Number of Mega Watts of Gas-fired Generation		40
Estimated Installation Capital Costs		63,200,000
Public Utilities, Return on Equity																																															0.1225		0.1081
Public Utilities, Regulatory Rate Increase																																																				0.398
Public Utilities, Collection of Deployment Costs Through Surcharge Period																																																						12 years
Public Utilities, Completion Period of Advanced Meter Deployment																																																						5 years
Public Utilities, Increase Annual Transmission Service Revenue																																														2,900,000
Public Utilities, Additional Revenue from Proposed Rates																																																									21,900,000	18,100,000
Public Utilities, Total Revenue Requirement Increase																																																			5,300,000						2,900,000	2,800,000
Public Utilities, Contract Extension																																																			10 years
Public Utilities, Estimated Increase in Revenue over amendment term																																																					3,100,000
Public Utilities, Approved Deployment Costs																																																						113,300,000
Public Utilities, Approved Program Implementation Costs																																																							4,800,000
Public Utilities, Approved Program Implementation Costs, Bonus																																																							400,000
Public Utilities, Unapproved 2014 Program Implementation Costs																																																								5,600,000
Public Utilities, Unapproved 2014 Program Implementation Costs, Expense																																																								4,700,000
Public Utilities, Unapproved 2014 Program Implementation Costs, Bonus																																																								700,000
Public Utilities, Unapproved 2014 Program Implementation Costs, Overcollection refund																																																								$ 100,000
Public Utilities, Retention Percentage of Sales Margins																																					10.00%
Public Utilities, Frequency of IRP filings																																													P3Y