Regulatory and Rate Matters - FPPAC Continuation Application (Details) - FPPAC Continuation Application [Member] - Public Service Company of New Mexico [Member] - USD ($) $ in Millions			12 Months Ended
	Apr. 30, 2014	Apr. 23, 2014	Dec. 31, 2013
Public Utilities, General Disclosures [Line Items]
Retention percentage of sales margins		10.00%
Under-collected balance write-off			$ 10.5
Under-collected balance to be recovered	$ 63.5
Period of time to collect		18 months