Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Earnings Per Share [Abstract]
Net Earnings Attributable to PNMR	$ 14,340		$ 12,468
Average Number of Common Shares:
Outstanding during period	79,654,000		79,654,000
Vested awards of restricted stock	112,000		182,000
Average Shares – Basic	79,766,000		79,836,000
Dilutive Effect of Common Stock Equivalents:
Stock options and restricted stock	387,000	[1]	551,000	[1]
Average Shares – Diluted	80,153,000		80,387,000
Net Earnings Per Share of Common Stock:
Basic (dollars per share)	$ 0.18		$ 0.16
Diluted (dollars per share)	$ 0.18		$ 0.16
Share Based Compensation Arrangement by Share Based Payment Award Options Outstanding Shares Above Entities Stock Price (in shares)	248,750

[1] Excludes the effect of out-of-the-money options for 248,750 shares of common stock at March 31, 2015.