Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (58,140)	$ (81,630)	$ (66,856)
Amounts reclassified from AOCI (pre-tax)	(8,152)	(5,385)	(32,476)
Income tax impact of amounts reclassified	3,234	2,137	12,865
Other OCI changes (pre-tax)	2,038	44,276	8,036
Income tax impact of other OCI changes	(735)us-gaap_OtherComprehensiveIncomeLossTax	(17,538)us-gaap_OtherComprehensiveIncomeLossTax	(3,199)us-gaap_OtherComprehensiveIncomeLossTax
Total Other Comprehensive Income (Loss)	(3,615)	23,490	(14,774)
Ending Balance	(61,755)	(58,140)	(81,630)
Percentage of Pension Liability Adjustment Capitalized into Construction Work In Process	24.40%	18.70%
Percentage of Pension Liability Adjustment Capitalized into Other Accounts	2.00%	3.00%
Public Service Company of New Mexico [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(57,877)	(81,414)	(66,798)
Amounts reclassified from AOCI (pre-tax)	(8,710)	(5,592)	(32,658)
Income tax impact of amounts reclassified	3,429	2,210	12,930
Other OCI changes (pre-tax)	2,191	44,555	8,464
Income tax impact of other OCI changes	(788)	(17,636)	(3,352)
Total Other Comprehensive Income (Loss)	(3,878)	23,537	(14,616)
Ending Balance	(61,755)	(57,877)	(81,414)
Texas-New Mexico Power Company [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(263)	(216)	(58)
Amounts reclassified from AOCI (pre-tax)	558	207	182
Income tax impact of amounts reclassified	(195)	(73)	(65)
Other OCI changes (pre-tax)	(153)	(279)	(428)
Income tax impact of other OCI changes	53	98	153
Total Other Comprehensive Income (Loss)	263	(47)	(158)
Ending Balance	0	(263)	(216)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	25,748	16,406	15,634
Amounts reclassified from AOCI (pre-tax)	(13,862)	(11,956)	(37,269)
Income tax impact of amounts reclassified	5,461	4,734	14,755
Other OCI changes (pre-tax)	17,473	27,419	38,548
Income tax impact of other OCI changes	(6,812)	(10,855)	(15,262)
Total Other Comprehensive Income (Loss)	2,260	9,342	772
Ending Balance	28,008	25,748	16,406
Accumulated Net Unrealized Investment Gain (Loss) [Member] \| Public Service Company of New Mexico [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	25,748	16,406	15,634
Amounts reclassified from AOCI (pre-tax)	(13,862)	(11,956)	(37,269)
Income tax impact of amounts reclassified	5,461	4,734	14,755
Other OCI changes (pre-tax)	17,473	27,419	38,548
Income tax impact of other OCI changes	(6,812)	(10,855)	(15,262)
Total Other Comprehensive Income (Loss)	2,260	9,342	772
Ending Balance	28,008	25,748	16,406
Accumulated Net Unrealized Investment Gain (Loss) [Member] \| Texas-New Mexico Power Company [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	0	0	0
Amounts reclassified from AOCI (pre-tax)	0	0	0
Income tax impact of amounts reclassified	0	0	0
Other OCI changes (pre-tax)	0	0	0
Income tax impact of other OCI changes	0	0	0
Total Other Comprehensive Income (Loss)	0	0	0
Ending Balance	0	0	0
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(83,625)	(97,820)	(82,432)
Amounts reclassified from AOCI (pre-tax)	5,152	6,364	4,611
Income tax impact of amounts reclassified	(2,032)	(2,524)	(1,825)
Other OCI changes (pre-tax)	(15,282)	17,136	(30,084)
Income tax impact of other OCI changes	6,024	(6,781)	11,910
Total Other Comprehensive Income (Loss)	(6,138)	14,195	(15,388)
Ending Balance	(89,763)	(83,625)	(97,820)
Accumulated Defined Benefit Plans Adjustment [Member] \| Public Service Company of New Mexico [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(83,625)	(97,820)	(82,432)
Amounts reclassified from AOCI (pre-tax)	5,152	6,364	4,611
Income tax impact of amounts reclassified	(2,032)	(2,524)	(1,825)
Other OCI changes (pre-tax)	(15,282)	17,136	(30,084)
Income tax impact of other OCI changes	6,024	(6,781)	11,910
Total Other Comprehensive Income (Loss)	(6,138)	14,195	(15,388)
Ending Balance	(89,763)	(83,625)	(97,820)
Accumulated Defined Benefit Plans Adjustment [Member] \| Texas-New Mexico Power Company [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	0	0	0
Amounts reclassified from AOCI (pre-tax)	0	0	0
Income tax impact of amounts reclassified	0	0	0
Other OCI changes (pre-tax)	0	0	0
Income tax impact of other OCI changes	0	0	0
Total Other Comprehensive Income (Loss)	0	0	0
Ending Balance	0	0	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(263)	(216)	(58)
Amounts reclassified from AOCI (pre-tax)	558	207	182
Income tax impact of amounts reclassified	(195)	(73)	(65)
Other OCI changes (pre-tax)	(153)	(279)	(428)
Income tax impact of other OCI changes	53	98	153
Total Other Comprehensive Income (Loss)	263	(47)	(158)
Ending Balance	0	(263)	(216)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Public Service Company of New Mexico [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	0	0	0
Amounts reclassified from AOCI (pre-tax)	0	0	0
Income tax impact of amounts reclassified	0	0	0
Other OCI changes (pre-tax)	0	0	0
Income tax impact of other OCI changes	0	0	0
Total Other Comprehensive Income (Loss)	0	0	0
Ending Balance	0	0	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] \| Texas-New Mexico Power Company [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(263)	(216)	(58)
Amounts reclassified from AOCI (pre-tax)	558	207	182
Income tax impact of amounts reclassified	(195)	(73)	(65)
Other OCI changes (pre-tax)	(153)	(279)	(428)
Income tax impact of other OCI changes	53	98	153
Total Other Comprehensive Income (Loss)	263	(47)	(158)
Ending Balance	$ 0	$ (263)	$ (216)

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Income tax impact of amounts reclassified from accumulated other comprehensive income

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Percentage of Pension Liability Adjustment Capitalized into Construction Work In Process

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Percentage of Pension Liability Adjustment Capitalized into Other Accounts

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount before tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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Amount before tax of reclassification adjustments of other comprehensive income (loss).

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