Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Equity [Abstract]
Percentage of Pension Liability Adjustment Capitalized into Construction Work In Process	22.80%	23.20%
Percentage of Pension Liability Adjustment Capitalized into Other Accounts	2.90%	2.70%
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (61,755)
Net change after income taxes	2,525	791
Ending Balance	(59,230)
PNMR and PNM [Member] \| Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	28,008	25,748
Amounts reclassified from AOCI (pre-tax)	(4,172)	(3,255)
Income tax impact of amounts reclassified	1,635	1,283
Other OCI changes (pre-tax)	6,836	3,379
Income tax impact of other OCI changes	(2,679)	(1,332)
Net change after income taxes	1,620	75
Ending Balance	29,628	25,823
PNMR and PNM [Member] \| Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(89,763)	(83,625)
Amounts reclassified from AOCI (pre-tax)	1,488	1,288
Income tax impact of amounts reclassified	(583)	(508)
Net change after income taxes	905	780
Ending Balance	(88,858)	(82,845)
PNM [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(61,755)	(57,877)
Amounts reclassified from AOCI (pre-tax)	(2,684)	(1,967)
Income tax impact of amounts reclassified	1,052	775
Other OCI changes (pre-tax)	6,836	3,379
Income tax impact of other OCI changes	(2,679)	(1,332)
Net change after income taxes	2,525	855
Ending Balance	(59,230)	(57,022)
Texas-New Mexico Power Company [Member] \| Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		(263)
Amounts reclassified from AOCI (pre-tax)		55
Income tax impact of amounts reclassified		(19)
Other OCI changes (pre-tax)		(153)
Income tax impact of other OCI changes		53
Net change after income taxes		(64)
Ending Balance		(327)
PNMR [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(61,755)	(58,140)
Amounts reclassified from AOCI (pre-tax)	(2,684)	(1,912)
Income tax impact of amounts reclassified	1,052	756
Other OCI changes (pre-tax)	6,836	3,226
Income tax impact of other OCI changes	(2,679)	(1,279)
Net change after income taxes	2,525	791
Ending Balance	$ (59,230)	$ (57,349)

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Income tax impact of amounts reclassified from accumulated other comprehensive income

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- Definition

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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