Number of allotment parcels' appraisal requested for review

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- Definition

Number of allotments where landowners are revoking rights of way renewal consents

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Number of landowners claiming to be Navajo allottees

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Public Utilities, Aggregate Amount of All Risk Insurance

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Public Utilities, Assessed Coal Severance Surtax Penalty and Interest

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Public Utilities, Current Surface Mining Royalty Rate applied between 2000 and 2003

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Public Utilities, Liability Insurance Coverage

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Public Utilities, Liability Insurance Coverage Sublimit

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Public Utilities, Maximum Amount under Nuclear Electric Insurance Limited

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Public Utilities, Maximum Potential Assessment Per Incident

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Public Utilities, Ownership Percentage in Nuclear Reactor

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Public Utilities, Proposed Retroactive Surface Mining Royalty Rate

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Commitments and Contingencies - Royalty Rates, Tax Assessment, Insurance and Other Matters (Details) (USD $)	Mar. 31, 2015	Apr. 01, 2014	Jan. 22, 2015 Allotment_Parcel	Apr. 02, 2014 Allotment_Parcel	Jan. 06, 2014 Allotment_Parcel	Sep. 30, 2012 Allotment_Parcel
Continuous Highwall Mining [Member] \| San Juan Generating Station [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, Proposed Retroactive Surface Mining Royalty Rate	12.50%
Public Utilities, Current Surface Mining Royalty Rate applied between 2000 and 2003	8.00%
Public Utilities, Estimated Underpaid Surface Mining Royalties under proposed rate change	$ 5,000,000
Public Utilities, PNM Share Estimated Underpaid Surface Mining Royalties under proposed rate change	46.30%
NMTRD Coal Severance Tax [Member] \| Four Corners [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, Assessed Coal Severance Surtax Penalty and Interest	30,000,000
Public Service Company of New Mexico [Member] \| Nuclear Plant [Member] \| Palo Verde Nuclear Generating Station [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, Ownership Percentage in Nuclear Reactor	10.20%
Public Utilities, Maximum Potential Assessment Per Incident	38,900,000
Public Utilities, Annual Payment Limitation Related to Incident	5,700,000
Public Utilities, Aggregate Amount of All Risk Insurance	2,750,000,000
Public Utilities, Maximum Amount under Nuclear Electric Insurance Limited	5,400,000
Public Service Company of New Mexico [Member] \| Nuclear Plant [Member] \| Maximum [Member] \| Palo Verde Nuclear Generating Station [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, Liability Insurance Coverage	13,600,000,000
Public Utilities, Liability Insurance Coverage Sublimit		2,250,000,000
Public Service Company of New Mexico [Member] \| NMTRD Coal Severance Tax [Member] \| Four Corners [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, PNM Share Assessed Coal Severance Surtax Penalty and Interest to pass through FFPAC	9.40%
Public Service Company of New Mexico [Member] \| Navajo Nation Allottee Matters [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Number of landowners claiming to be Navajo allottees						43
Number of allotment parcels' appraisal requested for review					58
Number of allotments where landowners are revoking rights of way renewal consents			10	6
Public Service Company of New Mexico [Member] \| Commercial Providers [Member] \| Nuclear Plant [Member] \| Palo Verde Nuclear Generating Station [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, Liability Insurance Coverage	375,000,000
Public Service Company of New Mexico [Member] \| Industry Wide Retrospective Assessment Program [Member] \| Nuclear Plant [Member] \| Palo Verde Nuclear Generating Station [Member]
Public Utilities, Commitments And Contingencies [Line Items]
Public Utilities, Liability Insurance Coverage	$ 13,200,000,000