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

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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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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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 ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net, Available-for-sale Securities	$ 1,200	$ (100)	$ 800	$ (600)
PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	253,550		253,550		$ 250,145
Available-for-sale Securities, Gross Unrealized Gain	39,797		39,797		46,348
Proceeds from sales	62,670	30,316	94,522	53,119
Gross realized gains	8,329	5,364	13,465	8,482
Gross realized (losses)	(1,578)	$ (755)	(3,119)	$ (1,794)
PNMR and PNM [Member] \| Cash and equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	3,940		3,940		8,276
Available-for-sale Securities, Gross Unrealized Gain	0		0		0
PNMR and PNM [Member] \| Domestic value [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	45,750		45,750		45,340
Available-for-sale Securities, Gross Unrealized Gain	15,015		15,015		17,418
PNMR and PNM [Member] \| Domestic growth [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	78,515		78,515		74,053
Available-for-sale Securities, Gross Unrealized Gain	19,850		19,850		21,354
PNMR and PNM [Member] \| International and other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	17,057		17,057		16,599
Available-for-sale Securities, Gross Unrealized Gain	1,147		1,147		156
PNMR and PNM [Member] \| U.S. Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	30,421		30,421		22,563
Available-for-sale Securities, Gross Unrealized Gain	276		276		903
PNMR and PNM [Member] \| Municipals [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	58,986		58,986		68,973
Available-for-sale Securities, Gross Unrealized Gain	3,098		3,098		5,851
PNMR and PNM [Member] \| Corporate and other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	18,881		18,881		14,341
Available-for-sale Securities, Gross Unrealized Gain	411		411		666
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	253,550		253,550		250,145
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Nuclear Decommissioning Trust [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	247,800		247,800		244,600
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Mine Reclamation Trust [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	5,700		5,700		5,500
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Cash and equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	3,940		3,940		8,276
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Domestic value [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	45,750		45,750		45,340
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Domestic growth [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	78,515		78,515		74,053
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| International and other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	17,057		17,057		16,599
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| U.S. Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	30,421		30,421		22,563
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Municipals [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	58,986		58,986		68,973
Fair Value, Measurements, Recurring [Member] \| PNMR and PNM [Member] \| Corporate and other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Fair value	$ 18,881		$ 18,881		$ 14,341