Goodwill and Other Intangible Assets; Impairments (Details) (USD $)				12 Months Ended							12 Months Ended					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Customer Lists [Member]	Dec. 31, 2008 Customer Lists [Member]	Dec. 31, 2008 Trade Names [Member]	Dec. 31, 2008 Texas-New Mexico Power Company [Member]	Dec. 31, 2013 Texas-New Mexico Power Company [Member]	Dec. 31, 2012 Texas-New Mexico Power Company [Member]	Apr. 02, 2012 Texas-New Mexico Power Company [Member]	Dec. 31, 2008 Public Service Company of New Mexico [Member]	Dec. 31, 2013 Public Service Company of New Mexico [Member]	Apr. 03, 2013 Public Service Company of New Mexico [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member]	Apr. 02, 2012 Public Service Company of New Mexico [Member]	Dec. 31, 2008 First Choice [Member]
Schedule of Goodwill and Other Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life				8 years
Goodwill	$ 278,297,000	$ 278,297,000	$ 278,297,000					$ 226,665,000	$ 226,665,000			$ 51,632,000		$ 51,632,000
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount										26.00%			27.00%		15.00%
Goodwill, Reporting Unit, Sensitivity analysis, Percentage Increase in Expected Return on Equity													0.50%
Goodwill, Reporting Unit, Sensitivity analysis, Reduced Percentage of Fair Value in Excess of Carrying Value													20.00%
Goodwill, Impairment Loss							34,500,000				51,100,000					88,800,000
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)						42,600,000
Impairment of Intangible Assets, Finite-lived					$ 4,800,000