Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Regulatory Assets
Current	$ 1,070	$ 47,855
Non-Current	470,664	491,007
Regulatory Liabilities
Current	(15,591)	(1,703)
Non-Current	(467,413)	(466,143)
Public Service Company of New Mexico [Member]
Regulatory Assets
Current	0	43,980
Non-Current	342,910	357,045
Total regulatory assets	342,910	401,025
Regulatory Liabilities
Current	(15,591)	(1,703)
Non-Current	(434,863)	(425,481)
Total regulatory liabilities	(450,454)	(427,184)
Public Service Company of New Mexico [Member] \| Fuel and Purchased Power Adjustment Clause [Member]
Regulatory Liabilities
Current	(11,410)	0
Public Service Company of New Mexico [Member] \| Other Current [Member]
Regulatory Liabilities
Current	(4,181)	(1,703)
Public Service Company of New Mexico [Member] \| Cost of removal [Member]
Regulatory Liabilities
Non-Current	(284,015)	(277,148)
Public Service Company of New Mexico [Member] \| Deferred income taxes [Member]
Regulatory Liabilities
Non-Current	(77,502)	(75,941)
Public Service Company of New Mexico [Member] \| AROs [Member]
Regulatory Liabilities
Non-Current	(33,747)	(35,834)
Public Service Company of New Mexico [Member] \| Renewable energy [Member]
Regulatory Liabilities
Non-Current	(23,697)	(24,854)
Public Service Company of New Mexico [Member] \| AMS surcharge [Member]
Regulatory Liabilities
Non-Current	0	0
Public Service Company of New Mexico [Member] \| Nuclear spent fuel, Reimbursement [Member]
Regulatory Liabilities
Non-Current	(9,214)	(3,625)
Public Service Company of New Mexico [Member] \| Pension and OPEB [Member]
Regulatory Liabilities
Non-Current	0	0
Public Service Company of New Mexico [Member] \| Other [Member]
Regulatory Liabilities
Non-Current	(6,688)	(8,079)
Public Service Company of New Mexico [Member] \| Fuel and Purchased Power Adjustment Clause [Member]
Regulatory Assets
Current	0	43,980
Public Service Company of New Mexico [Member] \| Transmission cost recovery factor [Member]
Regulatory Assets
Current	0	0
Public Service Company of New Mexico [Member] \| Energy efficiency costs [Member]
Regulatory Assets
Current	0	0
Public Service Company of New Mexico [Member] \| CTC, including carrying charges[Member]
Regulatory Assets
Non-Current	0	0
Public Service Company of New Mexico [Member] \| Coal mine reclamation costs [Member]
Regulatory Assets
Non-Current	28,303	34,224
Public Service Company of New Mexico [Member] \| Deferred income taxes [Member]
Regulatory Assets
Non-Current	66,990	63,645
Public Service Company of New Mexico [Member] \| Loss on reacquired debt [Member]
Regulatory Assets
Non-Current	23,627	25,439
Public Service Company of New Mexico [Member] \| Pension and OPEB [Member]
Regulatory Assets
Non-Current	218,743	222,545
Public Service Company of New Mexico [Member] \| AMS surcharge [Member]
Regulatory Assets
Non-Current	0	0
Public Service Company of New Mexico [Member] \| Advanced meter retirement costs [Member]
Regulatory Assets
Non-Current	0	0
Public Service Company of New Mexico [Member] \| Renewable energy [Member]
Regulatory Assets
Non-Current	0	5,263
Public Service Company of New Mexico [Member] \| Other [Member]
Regulatory Assets
Non-Current	5,247	5,929
Texas-New Mexico Power Company [Member]
Regulatory Assets
Current	1,070	3,875
Non-Current	127,754	133,962
Total regulatory assets	128,824	137,837
Regulatory Liabilities
Current	0	0
Non-Current	(32,550)	(40,662)
Total regulatory liabilities	(32,550)	(40,662)
Texas-New Mexico Power Company [Member] \| Fuel and Purchased Power Adjustment Clause [Member]
Regulatory Liabilities
Current	0	0
Texas-New Mexico Power Company [Member] \| Other Current [Member]
Regulatory Liabilities
Current	0	0
Texas-New Mexico Power Company [Member] \| Cost of removal [Member]
Regulatory Liabilities
Non-Current	(26,859)	(29,391)
Texas-New Mexico Power Company [Member] \| Deferred income taxes [Member]
Regulatory Liabilities
Non-Current	(3,283)	(3,923)
Texas-New Mexico Power Company [Member] \| AROs [Member]
Regulatory Liabilities
Non-Current	0	0
Texas-New Mexico Power Company [Member] \| Renewable energy [Member]
Regulatory Liabilities
Non-Current	0	0
Texas-New Mexico Power Company [Member] \| AMS surcharge [Member]
Regulatory Liabilities
Non-Current	0	(5,227)
Texas-New Mexico Power Company [Member] \| Nuclear spent fuel, Reimbursement [Member]
Regulatory Liabilities
Non-Current	0	0
Texas-New Mexico Power Company [Member] \| Pension and OPEB [Member]
Regulatory Liabilities
Non-Current	(1,913)	(2,121)
Texas-New Mexico Power Company [Member] \| Other [Member]
Regulatory Liabilities
Non-Current	(495)	0
Texas-New Mexico Power Company [Member] \| Fuel and Purchased Power Adjustment Clause [Member]
Regulatory Assets
Current	0	0
Texas-New Mexico Power Company [Member] \| Transmission cost recovery factor [Member]
Regulatory Assets
Current	441	2,482
Texas-New Mexico Power Company [Member] \| Energy efficiency costs [Member]
Regulatory Assets
Current	629	1,393
Texas-New Mexico Power Company [Member] \| CTC, including carrying charges[Member]
Regulatory Assets
Non-Current	46,147	55,292
Texas-New Mexico Power Company [Member] \| Coal mine reclamation costs [Member]
Regulatory Assets
Non-Current	0	0
Texas-New Mexico Power Company [Member] \| Deferred income taxes [Member]
Regulatory Assets
Non-Current	10,244	10,556
Texas-New Mexico Power Company [Member] \| Loss on reacquired debt [Member]
Regulatory Assets
Non-Current	35,405	36,703
Texas-New Mexico Power Company [Member] \| Pension and OPEB [Member]
Regulatory Assets
Non-Current	23,356	23,803
Texas-New Mexico Power Company [Member] \| AMS surcharge [Member]
Regulatory Assets
Non-Current	1,673	0
Texas-New Mexico Power Company [Member] \| Advanced meter retirement costs [Member]
Regulatory Assets
Non-Current	8,549	6,453
Texas-New Mexico Power Company [Member] \| Renewable energy [Member]
Regulatory Assets
Non-Current	0	0
Texas-New Mexico Power Company [Member] \| Other [Member]
Regulatory Assets
Non-Current	$ 2,380	$ 1,155

No definition available.

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- Definition

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
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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- References

No definition available.

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- Definition

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.

+ References

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- Definition

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.

+ References

+ Details

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- Definition

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
-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

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- Definition

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

+ References

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- Definition

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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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