Financing (Details) (USD $)	0 Months Ended				12 Months Ended						12 Months Ended					0 Months Ended		12 Months Ended					12 Months Ended	1 Months Ended	12 Months Ended					1 Months Ended		0 Months Ended				1 Months Ended	12 Months Ended		0 Months Ended			1 Months Ended
	Nov. 22, 2011	Nov. 04, 2011	Oct. 31, 2011	Oct. 05, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Oct. 24, 2011	Sep. 23, 2011	Oct. 24, 2011 Unsecured Debt [Member]	Dec. 31, 2011 Line of Credit [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member]	Dec. 31, 2009 Public Service Company of New Mexico [Member]	Oct. 31, 2011 Public Service Company of New Mexico [Member]	Jun. 09, 2010 Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Jul. 02, 2009 Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Dec. 31, 2003 Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Dec. 01, 2009 Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member]	Oct. 12, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member]	Oct. 06, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Line of Credit [Member]	Jan. 31, 2009 Texas-New Mexico Power Company [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [Member]	Dec. 31, 2009 Texas-New Mexico Power Company [Member]	Apr. 30, 2009 Texas-New Mexico Power Company [Member]	Jan. 02, 2009 Texas-New Mexico Power Company [Member]	Jan. 31, 2009 Texas-New Mexico Power Company [Member] Unsecured Debt [Member]	Jan. 02, 2009 Texas-New Mexico Power Company [Member] Unsecured Debt [Member]	Mar. 23, 2009 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member]	Mar. 30, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Mar. 25, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Mar. 23, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Jan. 31, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member] Line of Credit [Member]	Mar. 23, 2009 Texas-New Mexico Power Company [Member] Line of Credit [Member]	Sep. 30, 2011 Texas-New Mexico Power Company [Member] Notes Payable to Banks [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member] Notes Payable to Banks [Member]	Dec. 31, 2011 Maximum [Member]	Feb. 28, 2011 Unsecured Debt [Member]	Feb. 28, 2009 Unsecured Debt [Member]	Jan. 31, 2009 Unsecured Debt [Member]	Dec. 31, 2011 Borrowings from PNMR [Member] Texas-New Mexico Power Company [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity					$ 584,900,000							$ 244,000,000													$ 74,700,000
Letters of Credit Outstanding, Amount					11,100,000							4,700,000													300,000
Line of Credit Facility Original Maximum Borrowing Capacity					600,000,000							400,000,000
Debt Instrument, Face Amount	50,000,000																					160,000,000																					157,400,000
Debt Instrument, Interest Rate, Stated Percentage										9.25%								4.00%	6.25%			5.35%									6.25%	9.50%												9.25%
Gains (Losses) on Extinguishment of Debt	9,200,000				(9,209,000)	0	7,317,000																																			7,300,000
Debt Instrument, Unused Borrowing Capacity, Amount																																		50,000,000
Proceeds from Loans																																	50,000,000
Debt Instrument Issuance, Face Amount Percentage																					0.99857											0.97643
Debt Instrument, Decrease, Repayments																																										146,400,000
Preferred Stock, Shares Outstanding									477,800			115,293	115,293
Convertible Preferred Stock, Shares Issued upon Conversion									4,778,000
Preferred Stock Purchase Discount									0.02
Payments for Repurchase of Convertible Preferred Stock				73,500,000
Preferred Stock, Value, Outstanding				100,000,000
Unsecured Long-term Debt, Noncurrent								50,000,000
Debt Instrument, Repurchase Premium								0.17
Repayments of Unsecured Debt	58,500,000																													167,700,000
Common Stock, Shares, Outstanding		7,019,550			79,653,624	86,673,174						39,117,799	39,117,799												6,358	6,358
Common Stock Repurchase Discount		0.02
Payments for Repurchase of Common Stock		125,700,000			125,683,000	0	0
Stock Issued During Period, Shares, New Issues							93,328
Stock Issued During Period, Shares, Other							48,202
Proceeds from Issuance of Long-term Debt					210,000,000	403,845,000	345,242,000					160,000,000	403,845,000	36,000,000				36,000,000							50,000,000	0	309,242,000					265,500,000
Repayments of Long-term Debt					110,752,000	405,970,000	352,084,000					0	403,845,000	36,000,000			36,000,000								50,000,000	0	167,690,000								100,000,000
Proceeds from Pollution Control Bond																403,800,000
Proceeds from Callable Pollution Control Bond																403,800,000
Debt Instrument, Authorized Unsecured Debt Offering																						250,000,000
Debt Instrument, Shelf Registration Statement for Unsecured Debt																				440,000,000
Line of Credit Facility, Maximum Borrowing Capacity			300,000,000												400,000,000										75,000,000			75,000,000	200,000,000									150,000,000
Line of Credit Facility, Extension Option, Years			1 year
Line of Credit Facility, Increase, Additional Borrowings																								100,000,000
Debt Instrument, Amount Secured by Collateral																																	50,000,000						50,000,000
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum																																		6.05%					1.475%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum																																		6.30%					1.985%
Debt Instrument, Interest Rate, Effective Percentage																																							3.566%
Debt Instrument, Modified Interest Rate Stated Percentage RateRange Minimum																																				0.0480
Debt Instrument, Modified Interest Rate Stated Percentage Rate Maximum																																				0.0505
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value																										1,900,000														100,000
Intercompany Loans, Amount																									700,000	1,200,000															100,000,000				4,900,000
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value, Reported in Deferred Credits																										800,000
Proceeds from Bank Debt																																							50,000,000
Line of Credit Facility Reduction of Borrowing Capacity					$ 517,000,000							$ 368,000,000
Short-term Debt, Weighted Average Interest Rate					2.05%							1.80%
Ratio of debt to capital, maximum (as a percent)			65.00%								65.00%												65.00%														65.00%