Earnings and Dividends Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Earnings Per Share [Abstract]
Earnings Attributable to PNMR	$ 7,648	$ 54,555	$ 27,678	$ 10,626	$ 9,091	$ 57,864	$ 21,512	$ 17,080	$ 100,507		$ 105,547		$ 176,359
Average Number of Common Shares:
Outstanding during year									79,654,000		79,654,000		85,558,000
Equivalents from convertible preferred stock (Note 5)									0		0		3,469,000
Vested awards of restricted stock									191,000		145,000		174,000
Average Shares - Basic									79,845,000		79,799,000		89,201,000
Dilutive Effect of Common Stock Equivalents:
Stock options and restricted stock									586,000	[1]	618,000	[1]	556,000	[1]
Average Shares – Diluted									80,431,000	[1]	80,417,000	[1]	89,757,000	[1]
Net Earnings Per Share of Common Stock:
Basic (dollars per share)	$ 0.10	$ 0.68	$ 0.35	$ 0.13	$ 0.11	$ 0.73	$ 0.27	$ 0.21	$ 1.26		$ 1.32		$ 1.98
Diluted (dollars per share)	$ 0.10	$ 0.68	$ 0.34	$ 0.13	$ 0.11	$ 0.72	$ 0.27	$ 0.21	$ 1.25		$ 1.31		$ 1.96
Share Based Compensation Arrangement by Share Based Payment Award Options Outstanding Shares Above Entities Stock Price (in shares)									509,916
Common Stock, Dividends, Per Share, Declared									$ 0.68		$ 0.58		$ 0.50

[1] Excludes out-of-the-money options for 509,916 shares of common stock at December 31, 2013. See Note 13.