Fair Value of Derivative and Other Financial Instruments, Statement of Earnings Information (Details) (PNMR and PNM [Member], Commodity Contract [Member], Fair Value Hedging [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss)	$ (3,962)	$ (3,847)
Electric operating revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss)	(4,151)	(4,603)
Cost of energy [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss)	$ 189	$ 756