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

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Amount before tax of other than temporary impairment loss (OTTI) on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss and attributable to parent entity.

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The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

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The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities.

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Fair Value of Derivative and Other Financial Instruments, Available for Sale Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Realized impairment (loss) gain	$ 700,000	$ (600,000)	$ (5,200,000)
PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	250,145,000	226,855,000
Available-for-sale securities, Unrealized gains	46,348,000	42,602,000
Proceeds from sales	117,989,000	271,140,000	167,330,000
Gross realized gains	15,162,000	14,308,000	15,907,000
Gross realized (losses)	(3,964,000)	(4,298,000)	(8,170,000)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, before Tax, Portion Attributable to Parent	0
Cash and equivalents [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	8,276,000	3,356,000
Available-for-sale securities, Unrealized gains	0	0
Domestic value [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	45,340,000	39,460,000
Available-for-sale securities, Unrealized gains	17,418,000	14,523,000
Domestic growth [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	74,053,000	76,292,000
Available-for-sale securities, Unrealized gains	21,354,000	25,656,000
International and other [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	16,599,000	16,633,000
Available-for-sale securities, Unrealized gains	156,000	1,040,000
U.S. Government [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	22,563,000	21,941,000
Available-for-sale securities, Unrealized gains	903,000	158,000
Municipals [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	68,973,000	58,568,000
Available-for-sale securities, Unrealized gains	5,851,000	1,018,000
Corporate and other [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	14,341,000	10,605,000
Available-for-sale securities, Unrealized gains	666,000	207,000
Measured on a recurring basis [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	250,145,000	226,855,000
Measured on a recurring basis [Member] \| Nuclear Decommissioning Trust [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	244,600,000	222,500,000
Measured on a recurring basis [Member] \| Mine Reclamation Trust [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	5,500,000	4,400,000
Measured on a recurring basis [Member] \| Cash and equivalents [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	8,276,000	3,356,000
Measured on a recurring basis [Member] \| Domestic value [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	45,340,000	39,460,000
Measured on a recurring basis [Member] \| Domestic growth [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	74,053,000	76,292,000
Measured on a recurring basis [Member] \| International and other [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	16,599,000	16,633,000
Measured on a recurring basis [Member] \| U.S. Government [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	22,563,000	21,941,000
Measured on a recurring basis [Member] \| Municipals [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	68,973,000	58,568,000
Measured on a recurring basis [Member] \| Corporate and other [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	$ 14,341,000	$ 10,605,000