Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ (92,451)	$ (71,432)
Amounts reclassified from AOCI (pre-tax)			(3,412)	(1,926)
Income tax impact of amounts reclassified			1,324	751
Other OCI changes (pre-tax)			14,615	(3,441)
Income tax impact of other OCI changes			(5,671)	1,342
Total Other Comprehensive Income (Loss)	$ 2,863	$ 92	6,856	(3,274)
Ending Balance	(85,595)	(74,706)	(85,595)	(74,706)
Fair Value Adjustment for Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(23)	44
Amounts reclassified from AOCI (pre-tax)			323	371
Income tax impact of amounts reclassified			(125)	(145)
Other OCI changes (pre-tax)			(288)	(1,746)
Income tax impact of other OCI changes			112	681
Total Other Comprehensive Income (Loss)			22	(839)
Ending Balance	(1)	(795)	(1)	(795)
PNM
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(92,428)	(71,476)
Amounts reclassified from AOCI (pre-tax)			(3,735)	(2,297)
Income tax impact of amounts reclassified			1,449	896
Other OCI changes (pre-tax)			14,903	(1,695)
Income tax impact of other OCI changes			(5,783)	661
Total Other Comprehensive Income (Loss)	2,796	234	6,834	(2,435)
Ending Balance	(85,594)	(73,911)	(85,594)	(73,911)
PNM \| Unrealized Gains on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			4,320	17,346
Amounts reclassified from AOCI (pre-tax)			(6,961)	(5,049)
Income tax impact of amounts reclassified			2,701	1,970
Other OCI changes (pre-tax)			14,903	(1,695)
Income tax impact of other OCI changes			(5,783)	661
Total Other Comprehensive Income (Loss)			4,860	(4,113)
Ending Balance	9,180	13,233	9,180	13,233
PNM \| Pension Liability Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(96,748)	(88,822)
Amounts reclassified from AOCI (pre-tax)			3,226	2,752
Income tax impact of amounts reclassified			(1,252)	(1,074)
Total Other Comprehensive Income (Loss)			1,974	1,678
Ending Balance	$ (94,774)	$ (87,144)	$ (94,774)	$ (87,144)

Accumulated Other Comprehensive Income (Loss) [Roll Forward]

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- Definition

Income tax impact of amounts reclassified from accumulated other comprehensive income

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No definition available.

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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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