Income Taxes Schedule of Deferred Income Tax Components (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	$ 52,537
Change in tax effects of income tax related regulatory assets and liabilities	23,592
Tax effect of mark-to-market adjustments	(6,096)
Tax effect of excess pension liability	(9,305)
Adjustment for uncertain income tax positions	691
Other	(989)
Deferred income taxes	60,430	56,243	124,424
Public Service Company of New Mexico [Member]
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	41,697
Change in tax effects of income tax related regulatory assets and liabilities	23,704
Tax effect of mark-to-market adjustments	(6,121)
Tax effect of excess pension liability	(9,305)
Adjustment for uncertain income tax positions	691
Other	(623)
Deferred income taxes	50,043	65,479	90,567
Texas-New Mexico Power Company [Member]
Income Taxes [Line Items]
Net change in deferred income tax liability per above table	21,117
Change in tax effects of income tax related regulatory assets and liabilities	(112)
Other	(343)
Deferred income taxes	$ 20,662	$ 4,378	$ 15,478