Commitments and Contingencies (Commitments and Contingencies Related to the Environment) (Details) (USD $)											9 Months Ended			0 Months Ended																			0 Months Ended							12 Months Ended				3 Months Ended			0 Months Ended
	Dec. 21, 2011 mw	Sep. 30, 2014 Clean Air Act related to Regional Haze [Member] state	Dec. 21, 2011 San Juan Generating Station [Member]	Nov. 08, 2013 Public Service Company of New Mexico [Member] National Ambient Air Quality Standards [Member] San Juan Generating Station [Member]	Oct. 31, 2012 Public Service Company of New Mexico [Member] San Juan Generating Station [Member]	Oct. 31, 2012 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Clean Air Act, SCR [Member] [Member] Minimum [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Oct. 31, 2012 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Clean Air Act, SCR [Member] [Member] Maximum [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Dec. 20, 2013 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Clean Air Act, SNCR [Member] MW	Oct. 31, 2012 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Clean Air Act, SNCR [Member] Minimum [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Oct. 31, 2012 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Clean Air Act, SNCR [Member] Maximum [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Mercury Control [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station [Member] Mercury Control [Member] Maximum [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Units 2 and 3 [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Units 2 and 3 [Member] Clean Air Act, SNCR [Member]	Dec. 20, 2013 Public Service Company of New Mexico [Member] San Juan Generating Station Units 2 and 3 [Member] Clean Air Act, SNCR [Member] MW	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Units 2 and 3 [Member] Clean Air Act, SNCR [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Units 2 and 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station Unit 3 [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member]	Jun. 26, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Units 1 and 4 [Member]	Dec. 20, 2013 Public Service Company of New Mexico [Member] San Juan Generating Station Units 1 and 4 [Member] Clean Air Act, SNCR [Member] Maximum [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Units 1 and 4 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member] Maximum [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Jun. 26, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member] Clean Air Act, SNCR [Member]	Jun. 26, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member] Clean Air Act, SNCR [Member] MW	Dec. 20, 2013 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member] Clean Air Act, SNCR [Member] MW	Jun. 27, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member] Clean Air Act, SNCR [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Mar. 11, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member] Clean Air Act, SNCR [Member] Installation Costs Including Construction Management, Gross Receipts Taxes, AFUDC, and Other PNM Costs [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 4 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member] MW	Sep. 30, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member]	Dec. 20, 2013 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] MW	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member] Minimum [Member]	Oct. 01, 2014 Public Service Company of New Mexico [Member] San Juan Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member] Maximum [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Four Corners [Member] Clean Air Act Related to Post Combustion Controls [Member]	Aug. 06, 2012 Public Service Company of New Mexico [Member] Four Corners [Member] Clean Air Act Related to Post Combustion Controls [Member] compliance_alternative	Sep. 30, 2014 Public Service Company of New Mexico [Member] Four Corners Units 4 and 5 (Coal) [Member] Clean Air Act Related to Post Combustion Controls [Member]	Jan. 31, 2010 Public Service Company of New Mexico [Member] San Juan Generating Station And Four Corners [Member] Minimum [Member] opp	Jan. 31, 2010 Public Service Company of New Mexico [Member] San Juan Generating Station And Four Corners [Member] Maximum [Member] opp	Dec. 31, 2013 Public Service Company of New Mexico [Member] Nuclear Spent Fuel And Waste Disposal [Member] Palo Verde Nuclear Generating Station [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Nuclear Spent Fuel And Waste Disposal [Member] Palo Verde Nuclear Generating Station [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Nuclear Spent Fuel And Waste Disposal [Member] Palo Verde Nuclear Generating Station [Member] Other Deferred Credits [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member] Nuclear Spent Fuel And Waste Disposal [Member] Palo Verde Nuclear Generating Station [Member] Other Deferred Credits [Member]	Sep. 30, 2014 Public Service Company of New Mexico [Member] Nuclear Spent Fuel And Waste Disposal [Member] Palo Verde Nuclear Generating Station [Member] Settled Litigation [Member]	Sep. 30, 2014 PNMR and PNM [Member] Palo Verde Nuclear Generating Station Unit 3 [Member] MW	Dec. 20, 2013 PNMR and PNM [Member] Palo Verde Nuclear Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] MW	Oct. 01, 2014 PNMR and PNM [Member] Palo Verde Nuclear Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member]	Oct. 01, 2014 PNMR and PNM [Member] Palo Verde Nuclear Generating Station Unit 3 [Member] Clean Air Act, SNCR [Member] Subsequent Event [Member] MW	Sep. 30, 2014 Pnm Electric [Member] San Juan Generating Station Units 2 and 3 [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Lawsuit settlement, third party receipt																																												$ 57,400,000
PNMs share of lawsuit settlement, third party receipt																																												5,900,000
Loss Contingency, Estimate of Possible Loss																																			80,300,000						58,000,000
Loss Contingency Accrual																																										12,200,000	11,900,000
Annual Fee, Nuclear Waste Disposal																																								3,000,000
Revised Annual Fee, Nuclear Waste Disposal																																								0
Public Utilities, Number of States To Address Regional Haze		50
Public Utilities, Potential to emit tons per year of visibility impairing pollution, maximum		250
Estimated Total Capital Cost If Requirement Occurred						824,000,000	910,000,000
Estimated Installation Capital Costs									85,000,000	90,000,000											82,000,000	90,600,000
Estimated Portion of Total Capital Costs if Requirement Occured									105,000,000	110,000,000
Jointly Owned Utility Plant, Proportionate Ownership Share					46.30%
Public Utilities, Requested Time Period to Recover Retired Units NBV														20 years	20 years
Public Utilities, Number of Megawatts Nuclear Generation																																													134	134		134
Public Utilities, Proposed value per Kilowatt effective January 1, 2018																			1,650																											2,500
Public Utilities, Additional Ownership To Be Obtained, in Megawatts																									132	78			132
Public Utilities, Overall Reduction Of Ownership, in Megawatts								340
Public Utilities, Newly Identified Replacement Gas-fired Generation, in Megawatts, December2013															177
Public Utilities, Newly Identified Replacement Solar Generation, in Megawatts, December2013															40
Estimated cost of replacing gas fired peaking capacity due to retirement of SJGS units																																																	268,300,000
Public Utilities, Ownership To Be Exchanged, in Megawatts																															78
Public Utilities, Estimated rate base value at 1/1/2018																			221,100,000										26,000,000
Public Utilities, Proposed reduction in carrying value																																26,000,000
Public Utilities, Recovery Percentage of Estimated undepreciated value at 12/31/17																	50.00%
Public Utilities, Estimated undepreciated value at 12/31/17																	231,000,000
Net book value													284,000,000					143,000,000
Public Utilities, Percentage capacity factor 7-year performance threshold																																																75.00%
Public Utilities, Period over which to measure capacity performance																																															7 years
Public Utilities,Estimated unrecoverable increase in operations and maintenance																																20,000,000
Public Utilities, Write-off Percentage of Estimated undepreciated value at 12/31/17																50.00%
Public Utilities,Estimated pre-tax regulatory disallowance																																	60,000,000	70,000,000
Percentage of ownership held by exiting owners																								38.80%						50.00%
Public Utilities, Ownership Percentage																								38.50%						50.00%							13.00%
Public Utilities, Costs to obtain additional ownership																									0
Jointly Owned Utility Plan, Proposed Proportionate Ownership Share																				59.00%			64.50%
Requested Expenditure, Installation Capital Costs																												1,900,000
Requested Additional Expenditure, Installation Capital Costs																											6,400,000
Public Utilities, Number of Compliance alternatives																																				2
Public Utilities, Plant Requirement to Meet NOx emissions Limit																																			0.015
Public Utilities, Plant Requirement to Meet Opacity Limit, Percentage																																			20.00%
Public Utilities, Rule Imposes Opacity Limitation on Certain Fugitive Dust Emissions From Coal and Material Handling Operations																																			20.00%
Public Utilities, Revised SO2 Emissions Agreed Upon				0.1
Public Utilities, Government Standard Emission Limit																																						0.060	0.070
Current Annual Mercury Control Costs											700,000
Contingent Estimated Annual Mercury Control Cost												$ 6,600,000
Minimum Megawatt Capacity from Coal and Oil-Fired Electric Generating Units under Jurisdiction of the Mercury and Air Toxics Standards	25
Mercury Removal Rate, Percentage			99.00%