Financing (Details) (USD $)	0 Months Ended			12 Months Ended						12 Months Ended				0 Months Ended				12 Months Ended			0 Months Ended		1 Months Ended				0 Months Ended				12 Months Ended				12 Months Ended
	Nov. 22, 2011	Nov. 04, 2011	Oct. 05, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Oct. 24, 2011	Sep. 23, 2011	Oct. 24, 2011 Unsecured Debt [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member]	Apr. 30, 2012 Public Service Company of New Mexico [Member]	Jun. 09, 2010 Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Dec. 31, 2012 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, 2012 Texas-New Mexico Power Company [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [Member]	Mar. 23, 2009 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member]	Mar. 25, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Jan. 31, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Mar. 30, 2009 Texas-New Mexico Power Company [Member] Loans Payable [Member]	Dec. 31, 2012 Maximum [Member]	Feb. 22, 2013 Borrowings from PNMR [Member] Texas-New Mexico Power Company [Member]	Sep. 30, 2011 Notes Payable to Banks [Member] Texas-New Mexico Power Company [Member]	Dec. 31, 2012 Notes Payable to Banks [Member] Texas-New Mexico Power Company [Member]	Dec. 31, 2011 Notes Payable to Banks [Member] Texas-New Mexico Power Company [Member]	Dec. 31, 2012 PNMR Term Loan Agreement [Member]	Dec. 31, 2012 PNMR Term Loan Agreement [Member] Notes Payable to Banks [Member]	Dec. 14, 2012 PNMR Term Loan Agreement [Member] Notes Payable to Banks [Member]	Dec. 31, 2012 2.54% Maturing of September First, 2042 with a Mandatory Tender on June First, 2017 [Member] Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Dec. 31, 2012 5.15% Percent Maturing in 2037 [Member] Public Service Company of New Mexico [Member] Pollution Control Revenue Bonds [Member]	Dec. 31, 2012 New Mexico Public Regulation Commission [Member] Public Service Company of New Mexico [Member] Extensions
Debt Instrument [Line Items]
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, Interest Rate, Stated Percentage									9.25%								5.35%				9.50%												2.54%	5.15%
Debt Instrument, Refunded Amount Redeemed at Par and Retired																																		20,000,000
Debt Instrument, Repurchase Premium							0.17
Debt Instrument, Face Amount	50,000,000																160,000,000																20,000,000
Repayments of Unsecured Debt	58,500,000
Gains (Losses) on Extinguishment of Debt	9,200,000			0	(9,209,000)	0
Common stock, shares outstanding		7,019,550		79,653,624	79,653,624					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		0	125,683,000	0
Short-term debt				158,700,000	82,700,000					21,100,000	66,000,000																			100,000,000		100,000,000
Proceeds from Short-term Debt				100,000,000	0	0																									100,000,000
Repayments of Lines of Credit																															100,000,000
Proceeds from Pollution Control Bond														403,800,000
Proceeds from Callable Pollution Control Bond														403,800,000
Debt Instrument Issuance, Face Amount Percentage																0.99857
Debt Instrument, Requested Approval to Refinance Debt													20,000,000
Line of Credit Facility, Number of Extension Options Received Authority To Exercise																																			2
Line of Credit Facility, Extension Option Granted Authority To Exercise, Years																																			1 year
Debt Instrument, Shelf Registration Statement for Unsecured Debt															440,000,000
Proceeds from Issuance of Long-term Debt				20,000,000	210,000,000	403,845,000				20,000,000	160,000,000	403,845,000						0	50,000,000	0	265,500,000
Debt Instrument, Unused Borrowing Capacity, Amount																						50,000,000
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, Modified Interest Rate Stated Percentage Rate Range Minimum																							0.0480
Debt Instrument, Modified Interest Rate Stated Percentage Rate Maximum																							0.0505
Proceeds from Bank Debt																											50,000,000
Debt Instrument, Interest Rate, Effective Percentage																												3.566%
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value																												300,000	100,000
Intercompany Loans, Amount																		$ 28,300,000	$ 700,000						$ 100,000,000	$ 10,400,000