Regulatory Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Regulatory Assets
Regulatory Assets, Current	$ 47,855us-gaap_RegulatoryAssetsCurrent	$ 24,416us-gaap_RegulatoryAssetsCurrent
Regulatory Assets, Noncurrent	491,007us-gaap_RegulatoryAssetsNoncurrent	523,955us-gaap_RegulatoryAssetsNoncurrent
Regulatory Liabilities
Regulatory Liability, Current	(1,703)us-gaap_RegulatoryLiabilityCurrent	(1,081)us-gaap_RegulatoryLiabilityCurrent
Regulatory liabilities, Noncurrent	(466,143)us-gaap_RegulatoryLiabilityNoncurrent	(460,649)us-gaap_RegulatoryLiabilityNoncurrent
Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Current	43,980	19,394
Regulatory Assets, Noncurrent	357,045	384,217
Regulatory Assets	401,025	403,611
Regulatory Liabilities
Regulatory Liability, Current	(1,703)	(1,081)
Regulatory liabilities, Noncurrent	(425,481)	(414,611)
Regulatory Liabilities	(427,184)	(415,692)
Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Current	3,875	5,022
Regulatory Assets, Noncurrent	133,962	139,738
Regulatory Assets	137,837	144,760
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(40,662)	(46,038)
Removal Costs [Member] \| Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(277,148)	(266,075)
Removal Costs [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(29,391)	(30,863)
Deferred Income Tax Charge [Member] \| Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(75,941)	(80,495)
Deferred Income Tax Charge [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(3,923)	(4,563)
Asset Retirement Obligation Costs [Member] \| Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(35,834)	(37,567)
Renewable Energy Program [Member] \| Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(24,854)	(26,011)
Other Regulatory Assets (Liabilities) [Member] \| Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(11,704)	(4,463)
Other Regulatory Assets (Liabilities) [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(2,121)	(3,361)
Advanced Metering Infrastructure Costs [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(5,227)	(7,251)
Regulatory Assets, Transmission Cost Recovery [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Current	2,482	4,250
Other Regulatory Assets (Liabilities) [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	5,929	9,345
Other Regulatory Assets (Liabilities) [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Current	1,393	772
Regulatory Assets, Noncurrent	1,155	1,627
Stranded costs [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	55,292	63,606
Environmental Restoration Costs [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	34,224	40,144
Deferred Income Tax Charge [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	63,645	61,850
Deferred Income Tax Charge [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	10,556	10,868
Loss on reacquired debt [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	25,439	27,490
Loss on reacquired debt [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	36,703	38,616
Pension and Other Postretirement Plans Costs [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	222,545	206,691
Pension and Other Postretirement Plans Costs [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	23,803	19,938
Fuel and purchased power adjustment clause [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	0	25,386
Renewable Energy Program [Member] \| Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	5,263	13,311
Advanced Metering Infrastructure Costs [Member] \| Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	$ 6,453	$ 5,083

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 340

-Section 50

-Paragraph 1

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

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Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

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The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 405

-Section 25

-Paragraph 1

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The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

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The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.24)

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