Fair Value of Derivative and Other Financial Instruments, Debt Maturities (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
PNM Resources [Member]
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Held-to-maturity debt securities, Due within 1 year	$ 7,519
Held-to-maturity debt securities, After 1 year through 5 years	67,362
Held-to-maturity debt securities, After 5 years through 10 years	0
Held-to-maturity debt securities	74,881
Public Service Company of New Mexico [Member]
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Held-to-maturity debt securities, Due within 1 year	3,819
Held-to-maturity debt securities, After 1 year through 5 years	66,018
Held-to-maturity debt securities, After 5 years through 10 years	0
Held-to-maturity debt securities	69,837
PNMR and PNM [Member]
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale debt securities, Within 1 year	1,470
Available-for-sale debt securities, After 1 year through 5 years	18,713
Available-for-sale debt securities, After 5 years through 10 years	8,334
Available-for-sale debt securities, After 10 years through 15 years	7,887
Available-for-sale debt securities, After 15 years through 20 years	10,616
Available-for-sale debt securities, After 20 years	18,948
Available-for-sale debt securities	$ 65,968

Available-for-sale Securities, Debt Maturities, after Fifteen Years Through Twenty Years, Fair Value

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Available-for-sale Securities, Debt Maturities, after Ten Years Through Fifteen Years, Fair Value

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Available-for-sale Securities, Debt Maturities, after Twenty Years, Fair Value

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Amount of available-for-sale debt securities at fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at fair value maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at fair value maturing in the next fiscal year following the latest fiscal year.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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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.

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Amount of held-to-maturity debt securities at fair value maturing in the next fiscal year following the latest fiscal year.

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