Fair Value of Derivative and Other Financial Instruments, Defined Benefit Plans Disclosure (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 506,605	$ 453,986
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	200,397	239,289
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	207,520	122,098
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	98,688	92,599
PNMR Master Trust [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	62,139	60,506
PNMR Master Trust [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	444,466	393,480
PNMR Master Trust [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	24,118	30,530
PNMR Master Trust [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	176,279	208,759
PNMR Master Trust [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	23,466	16,317
PNMR Master Trust [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	184,054	105,781
PNMR Master Trust [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,555	13,659	12,426
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	280	(199)
Defined Benefit Plan, Actual Return on Plan Assets Still Held	243	1,024
Defined Benefit Plan Assets, Purchases	695	8,602
Defined Benefit Plan Assets, Sales	(322)	(8,194)
PNMR Master Trust [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	84,133	78,940	74,105
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1,624	(778)
Defined Benefit Plan, Actual Return on Plan Assets Still Held	1,404	4,015
Defined Benefit Plan Assets, Purchases	4,030	33,731
Defined Benefit Plan Assets, Sales	(1,865)	(32,133)
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6,753	10,718
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6,753	10,718
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Equity Securities, International Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	37,173	46,505
Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	37,173	46,505
Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Equity Securities, Domestic Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	58,350	79,218
Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	57,437	76,493
Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	913	2,725
Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Equity Securities, Domestic Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	65,004	81,375
Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	65,004	81,375
Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		49,682
Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Fixed Income Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		49,682
Fixed Income Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Equity Securities, Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	15,271	49,307
Equity Securities, Other [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Equity Securities, Other [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	15,271	49,307
Equity Securities, Other [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Securities, Corporate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	59,730	2,062
Fixed Income Securities, Corporate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Securities, Corporate [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	59,730	2,062
Fixed Income Securities, Corporate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Securities, U.S. Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	104,102	39,585
Fixed Income Securities, U.S. Government [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	34,030	24,198
Fixed Income Securities, U.S. Government [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	70,072	15,387
Fixed Income Securities, U.S. Government [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Securities, Municipals [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,478	2,935
Fixed Income Securities, Municipals [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Securities, Municipals [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,478	2,935
Fixed Income Securities, Municipals [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fixed Income Securities, Other Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	58,056
Fixed Income Securities, Other Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Fixed Income Securities, Other Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	58,056
Fixed Income Securities, Other Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	37,100	32,935
Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	37,100	32,935	26,883
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1,904	(769)
Defined Benefit Plan, Actual Return on Plan Assets Still Held	2,372	2,363
Defined Benefit Plan Assets, Purchases	2,076	39,255
Defined Benefit Plan Assets, Sales	(2,187)	(34,797)
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	36,904	37,622
Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	36,904	37,622	34,921
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	0
Defined Benefit Plan, Actual Return on Plan Assets Still Held	(718)	2,701
Defined Benefit Plan Assets, Purchases	0	0
Defined Benefit Plan Assets, Sales	0	0
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	24,684	22,042
Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Real Estate [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	24,684	22,042	24,727
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	(208)
Defined Benefit Plan, Actual Return on Plan Assets Still Held	(7)	(25)
Defined Benefit Plan Assets, Purchases	2,649	3,078
Defined Benefit Plan Assets, Sales	0	(5,530)
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0	2,168
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period		(1,846)
Defined Benefit Plan, Actual Return on Plan Assets Still Held		0
Defined Benefit Plan Assets, Purchases		0
Defined Benefit Plan Assets, Sales		(322)
Private Equity, Hedge and Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	98,688	92,599	86,531
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1,904
Defined Benefit Plan, Actual Return on Plan Assets Still Held	1,647	5,039
Defined Benefit Plan Assets, Purchases	4,725	42,333
Defined Benefit Plan Assets, Sales	(2,187)	(40,327)
Private Equity, Hedge and Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period		(977)
Other Postretirement Benefits [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8,303	8,596	7,093
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period	8,459	8,625
Other Postretirement Benefits [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	58,776	61,749	57,126
Defined Benefit Plan, Fair Value of Plan Total Assets Owned At the End of Period	59,857	62,551
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,163	4,550
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	28,638	31,973
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,296	4,075
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	31,219	30,578
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	180	424
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,128	1,811
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	180	424
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,128	1,811
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,248	1,116
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,740	3,182
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,248	1,116
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,740	3,182
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, International Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	551	582
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,289	1,363
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	551	582
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,289	1,363
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Value [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	738	710
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	43,016	41,278
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	738	710
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	22,215	22,939
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,801	18,339
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Domestic Growth [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,694	2,834
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,006	5,860
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2,694	2,834
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,006	5,860
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Fixed Income Funds [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,048	2,959
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	7,678	9,057
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Fair Value, Inputs, Level 1 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Fair Value, Inputs, Level 1 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Fair Value, Inputs, Level 2 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,048	2,959
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Fair Value, Inputs, Level 2 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	7,678	9,057
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Fair Value, Inputs, Level 3 [Member] | Texas-New Mexico Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefits [Member] | Equity Securities, Other [Member] | Fair Value, Inputs, Level 3 [Member] | Public Service Company of New Mexico [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0