Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Allowance for uncollectible accounts	$ 1,466	$ 1,423
Accumulated depreciation, nuclear fuel	44,507pnm_AccumulatedAmortizationNuclearFuel	47,347pnm_AccumulatedAmortizationNuclearFuel
Cumulative preferred stock of subsidiary, stated value	$ 100	$ 100
Cumulative preferred stock of subsidiary, shares authorized	10,000,000	10,000,000
Cumulative preferred stock of subsidiary, shares issued	115,293	115,293
Cumulative preferred stock of subsidiary, shares outstanding	115,293	115,293
Common stock, par value	$ 0us-gaap_CommonStockNoParValue	$ 0us-gaap_CommonStockNoParValue
Common stock, shares authorized	120,000,000us-gaap_CommonStockSharesAuthorized	120,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	79,653,624us-gaap_CommonStockSharesIssued	79,653,624us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	79,653,624us-gaap_CommonStockSharesOutstanding	79,653,624us-gaap_CommonStockSharesOutstanding
Cumulative preferred stock of subsidiary, shares authorized	10,000,000us-gaap_PreferredStockSharesAuthorized
Public Service Company of New Mexico [Member]
Allowance for uncollectible accounts	1,466	1,423
Accumulated depreciation, nuclear fuel	$ 44,507	$ 47,347
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	39,117,799	39,117,799
Common stock, shares outstanding	39,117,799	39,117,799
Cumulative preferred stock of subsidiary, stated value	$ 100	$ 100
Cumulative preferred stock of subsidiary, shares authorized	10,000,000	10,000,000
Cumulative preferred stock of subsidiary, shares issued	115,293	115,293
Cumulative preferred stock of subsidiary, shares outstanding	115,293	115,293
Texas-New Mexico Power Company [Member]
Common stock, shares authorized	12,000,000	12,000,000
Common stock, shares issued	6,358	6,358
Common stock, shares outstanding	6,358	6,358
Common stock, par value	$ 10	$ 10
Cumulative preferred stock of subsidiary, shares authorized	1,000,000

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