Income Taxes - Schedule of Deferred Income Tax Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	$ 63,257
Change in tax effects of income tax related regulatory assets and liabilities	(10,621)
Tax effect of mark-to-market adjustments	8,379
Tax effect of excess pension liability	5,071
Adjustment for uncertain income tax positions	297
Reclassification of unrecognized tax benefits	(297)
Regulatory recovery of prior year impairment of state net operating loss carryforward, net of amortization	(1,877)
Other	(404)
Deferred income taxes	63,805	$ 16,451	$ 72,481
Public Service Company of New Mexico [Member]
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	52,282
Change in tax effects of income tax related regulatory assets and liabilities	(10,510)
Tax effect of mark-to-market adjustments	8,336
Tax effect of excess pension liability	5,071
Adjustment for uncertain income tax positions	297
Reclassification of unrecognized tax benefits	(297)
Regulatory recovery of prior year impairment of state net operating loss carryforward, net of amortization	(1,877)
Other	(183)
Deferred income taxes	53,119	(2,836)	55,787
Texas-New Mexico Power Company [Member]
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	12,994
Change in tax effects of income tax related regulatory assets and liabilities	(111)
Other	(221)
Deferred income taxes	$ 12,662	$ 20,883	$ 20,549