Income Taxes Schedule of Deferred Income Tax Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	$ 12,665
Change in tax effects of income tax related regulatory assets and liabilities	(1,896)
Tax effect of mark-to-market adjustments	6,844
Tax effect of excess pension liability	(607)
Reclassification of unrecognized tax benefits	(8,576)
Reclassification of unrecognized tax benefits	8,576
Other	(555)
Deferred income taxes	16,451	$ 72,481	$ 60,430
Public Service Company of New Mexico [Member]
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	(7,012)
Change in tax effects of income tax related regulatory assets and liabilities	(1,784)
Tax effect of mark-to-market adjustments	6,872
Tax effect of excess pension liability	(607)
Reclassification of unrecognized tax benefits	(8,576)
Reclassification of unrecognized tax benefits	8,576
Other	(305)
Deferred income taxes	(2,836)	55,787	50,043
Texas-New Mexico Power Company [Member]
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	21,244
Change in tax effects of income tax related regulatory assets and liabilities	(111)
Other	(250)
Deferred income taxes	$ 20,883	$ 20,549	$ 20,662