Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Earnings Per Share [Abstract]
Net Earnings Attributable to PNMR	$ 55,653		$ 54,555		$ 97,262		$ 92,859
Average Number of Common Shares:
Outstanding during period	79,654,000		79,654,000		79,654,000		79,654,000
Vested awards of restricted stock	112,000		177,000		134,000		194,000
Average Shares – Basic	79,766,000		79,831,000		79,788,000		79,848,000
Dilutive Effect of Common Stock Equivalents:
Stock options and restricted stock	457,000	[1]	503,000	[1]	491,000	[1]	608,000	[1]
Average Shares – Diluted	80,223,000		80,334,000		80,279,000		80,456,000
Net Earnings Per Share of Common Stock:
Basic (dollars per share)	$ 0.70		$ 0.68		$ 1.22		$ 1.16
Diluted (dollars per share)	$ 0.69		$ 0.68		$ 1.21		$ 1.15
Share Based Compensation Arrangement by Share Based Payment Award Options Outstanding Shares Above Entities Stock Price (in shares)					435,472

[1] Excludes the effect of out-of-the-money options for 435,472 shares of common stock at September 30, 2014.