Fair Value of Derivative and Other Financial Instruments, Debt Maturities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
PNM Resources [Member]
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Held-to-maturity debt securities, Due within 1 year	$ 949
Held-to-maturity debt securities, After 1 year through 5 years	98,804
Held-to-maturity debt securities, After 5 years through 10 years	2,102
Held-to-maturity debt securities, Over 10 years	0
Held-to-maturity debt securities	101,855
Public Service Company of New Mexico [Member]
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Held-to-maturity debt securities, Due within 1 year	949
Held-to-maturity debt securities, After 1 year through 5 years	91,746
Held-to-maturity debt securities, After 5 years through 10 years	0
Held-to-maturity debt securities, Over 10 years	0
Held-to-maturity debt securities	92,695
PNMR and PNM [Member]
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Available-for-sale debt securities, Within 1 year	2,087
Available-for-sale debt securities, After 1 year through 5 years	21,540
Available-for-sale debt securities, After 5 years through 10 years	13,221
Available-for-sale debt securities, Over 10 years	42,104
Available-for-sale debt securities	$ 78,952

This item represents the fair value of debt securities which are expected to mature after five years and through ten years from the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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+ References

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This item represents the fair value of debt securities which are expected to mature after ten years from the balance sheet date which are categorized neither as held-to-maturity nor trading securities.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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This item represents the fair value of debt securities which are expected to mature within one year of the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

+ References

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-Publisher FASB

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For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

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+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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+ References

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+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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This item represents the total of all debt securities grouped by maturity dates, at fair value, which are categorized as held-to-maturity.

+ References

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

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-Name Accounting Standards Codification

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This item represents the fair value of debt securities which are expected to mature within one year of the balance sheet date and which are categorized as held-to-maturity.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 20

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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