Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 1,675,952
Amounts reclassified from AOCI (pre-tax)	(10,534)	$ (15,871)	$ (22,579)
Income tax impact of amounts reclassified	4,087	6,193	8,849
Other OCI changes (pre-tax)	32,778	(18,597)	6,665
Income tax impact of other OCI changes	(12,234)	7,256	(2,612)
Total Other Comprehensive Income (Loss)	14,097	(21,019)	(9,677)
Reclassification of stranded income taxes to retained earnings	(17,586)
Ending Balance	1,695,253	1,675,952
Public Service Company of New Mexico
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1,397,872
Amounts reclassified from AOCI (pre-tax)	(11,115)	(16,635)	(22,579)
Income tax impact of amounts reclassified	4,312	6,491	8,849
Other OCI changes (pre-tax)	31,778	(17,723)	6,593
Income tax impact of other OCI changes	(11,846)	6,915	(2,584)
Total Other Comprehensive Income (Loss)	13,129	(20,952)	(9,721)
Reclassification of stranded income taxes to retained earnings	(17,794)
Ending Balance	1,422,174	1,397,872
AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(92,451)	(71,432)	(61,755)
Total Other Comprehensive Income (Loss)	14,097	(21,019)	(9,677)
Reclassification of stranded income taxes to retained earnings	(17,586)
Ending Balance	(95,940)	(92,451)	(71,432)
AOCI \| Public Service Company of New Mexico
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(92,428)	(71,476)	(61,755)
Total Other Comprehensive Income (Loss)	13,129	(20,952)	(9,721)
Reclassification of stranded income taxes to retained earnings	(17,794)
Ending Balance	(97,093)	(92,428)	(71,476)
Unrealized Gains on Available-for-Sale Securities \| Public Service Company of New Mexico
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	4,320	17,346	28,008
Amounts reclassified from AOCI (pre-tax)	(17,567)	(22,139)	(28,531)
Income tax impact of amounts reclassified	6,816	8,639	11,181
Other OCI changes (pre-tax)	28,160	778	10,998
Income tax impact of other OCI changes	(10,927)	(304)	(4,310)
Total Other Comprehensive Income (Loss)	6,482	(13,026)	(10,662)
Reclassification of stranded income taxes to retained earnings	2,367
Ending Balance	13,169	4,320	17,346
Pension Liability Adjustment \| Public Service Company of New Mexico
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(96,748)	(88,822)	(89,763)
Amounts reclassified from AOCI (pre-tax)	6,452	5,504	5,952
Income tax impact of amounts reclassified	(2,504)	(2,148)	(2,332)
Other OCI changes (pre-tax)	3,618	(18,501)	(4,405)
Income tax impact of other OCI changes	(919)	7,219	1,726
Total Other Comprehensive Income (Loss)	6,647	(7,926)	941
Reclassification of stranded income taxes to retained earnings	(20,161)
Ending Balance	(110,262)	(96,748)	(88,822)
Fair Value Adjustment for Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(23)	44	0
Amounts reclassified from AOCI (pre-tax)	581	764	0
Income tax impact of amounts reclassified	(225)	(298)	0
Other OCI changes (pre-tax)	1,000	(874)	72
Income tax impact of other OCI changes	(388)	341	(28)
Total Other Comprehensive Income (Loss)	968	(67)	44
Reclassification of stranded income taxes to retained earnings	208
Ending Balance	$ 1,153	$ (23)	$ 44

Income tax impact of amounts reclassified from accumulated other comprehensive income

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Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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