Fair Value of Derivative and Other Financial Instruments, Available for Sale Securities (Details) (PNMR and PNM [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	$ 42,725		$ 42,602
Available-for-sale securities, Fair value	230,250		226,855
Proceeds from sales	22,804	14,284
Gross realized gains	3,119	1,391
Gross realized (losses)	(545)	(407)
Cash and equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	0		0
Available-for-sale securities, Fair value	4,246		3,356
Domestic value [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	14,558		14,523
Available-for-sale securities, Fair value	41,055		39,460
Domestic growth [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	23,002		25,656
Available-for-sale securities, Fair value	74,517		76,292
International and other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	1,671		1,040
Available-for-sale securities, Fair value	17,264		16,633
U.S. Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	377		158
Available-for-sale securities, Fair value	20,662		21,941
Municipals [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	2,659		1,018
Available-for-sale securities, Fair value	61,158		58,568
Corporate and other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Unrealized gains	458		207
Available-for-sale securities, Fair value	11,348		10,605
Fair Value, Measurements, Recurring [Member] \| Nuclear Decommissioning Trust [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	225,800		222,500
Fair Value, Measurements, Recurring [Member] \| Mine Reclamation Trust [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	$ 4,400		$ 4,400

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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