Segment Information (Narrative and Major Customers) (Details) (Sales [Member])	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
First Choice [Member]
Concentration Risk [Line Items]
Operating revenues from continuing operations (as a percent)	17.00%	19.00%	17.00%
Unaffiliated Customer of Texas-New Mexico Power Company One [Member]
Concentration Risk [Line Items]
Operating revenues from continuing operations (as a percent)	16.00%	17.00%	19.00%
Unaffiliated Customer of Texas-New Mexico Power Company Two [Member]
Concentration Risk [Line Items]
Operating revenues from continuing operations (as a percent)	10.00%	10.00%	12.00%
PNMR and PNM [Member] | Maximum [Member]
Concentration Risk [Line Items]
Operating revenues from continuing operations (as a percent)	10.00%