Financing Schedule of Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Oct. 24, 2011	Dec. 31, 2010	Oct. 24, 2011 Unsecured Debt [Member]	Dec. 31, 2011 Unsecured Debt [Member] Senior unsecured notes, 9.25% due 2015 [Member]	Dec. 31, 2010 Unsecured Debt [Member] Senior unsecured notes, 9.25% due 2015 [Member]	Dec. 31, 2011 Other [Member]	Dec. 31, 2010 Other [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 4.875% due 2033 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 4.875% due 2033 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.15% due 2037 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.15% due 2037 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 6.25% due 2038 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 6.25% due 2038 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 4.75% due 2040, mandatory tender at June 1, 2017 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 4.75% due 2040, mandatory tender at June 1, 2017 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.20% due 2040, mandatory tender at June 1, 2020 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.20% due 2040, mandatory tender at June 1, 2020 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.90% due 2040 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.90% due 2040 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 6.25% due 2040 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 6.25% due 2040 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 4.00% due 2043, mandatory tender at June 1, 2015 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 4.00% due 2043, mandatory tender at June 1, 2015 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.20% due 2043, mandatory tender at June 1, 2020 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] 5.20% due 2043, mandatory tender at June 1, 2020 [Member]	Oct. 06, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member] 7.95% due 2018 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Unsecured Debt [Member] 7.95% due 2018 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member] 7.50% due 2018 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Unsecured Debt [Member] 7.50% due 2018 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Unsecured Debt [Member] 5.35% due 2021 [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Unsecured Debt [Member] 5.35% due 2021 [Member]	Dec. 31, 2011 Public Service Company of New Mexico [Member] Other [Member]	Dec. 31, 2010 Public Service Company of New Mexico [Member] Other [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [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]	Dec. 31, 2011 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member] 2009 Term Loan Agreement, due 2014 [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member] 2009 Term Loan Agreement, due 2014 [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member] 2011 Term Loan Agreement, due 2014 [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member] 2011 Term Loan Agreement, due 2014 [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member] 9.50% due 2019, Series 2009A [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [Member] First Mortgage Bonds [Member] 9.50% due 2019, Series 2009A [Member]	Dec. 31, 2011 Texas-New Mexico Power Company [Member] Other [Member]	Dec. 31, 2010 Texas-New Mexico Power Company [Member] Other [Member]	Dec. 31, 2011 PNMR [Member]	Dec. 31, 2010 PNMR [Member]	Dec. 31, 2011 PNMR [Member] Unsecured Debt [Member] Senior unsecured notes, 9.25% due 2015 [Member]	Dec. 31, 2010 PNMR [Member] Unsecured Debt [Member] Senior unsecured notes, 9.25% due 2015 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				9.25%							4.875%	4.875%	5.15%	5.15%	6.25%	6.25%	4.75%	4.75%	5.20%	5.20%	5.90%	5.90%	6.25%	6.25%	4.00%	4.00%	5.20%	5.20%	5.35%	7.95%	7.95%	7.50%	7.50%	5.35%	5.35%					6.25%	9.50%					9.50%	9.50%					9.25%	9.25%
Unsecured Long-term Debt, Noncurrent		$ 50,000			$ 142,592	$ 192,592	$ 4,918	$ 7,170			$ 146,000	$ 146,000	$ 20,000	$ 20,000	$ 36,000	$ 36,000	$ 37,000	$ 37,000	$ 40,045	$ 40,045	$ 255,000	$ 255,000	$ 11,500	$ 11,500	$ 39,300	$ 39,300	$ 21,000	$ 21,000		$ 350,000	$ 350,000	$ 100,025	$ 100,025	$ 160,000	$ 0							$ 50,000	$ 0	$ 0	$ 50,000	$ 265,500	$ 265,500
Other, including unamortized discounts																																				(330)	(122)											(4,537)	(5,163)
Long-term Debt	1,674,013		1,565,847						1,215,540	1,055,748																												310,963	310,337											147,510	199,762
Long-term Debt, Current Maturities	2,387		2,252						0	0																												0	0											2,387	2,252
Long-term Debt, Excluding Current Maturities	$ 1,671,626		$ 1,563,595						$ 1,215,540	$ 1,055,748																												$ 310,963	$ 310,337											$ 145,123	$ 197,510