Fair Value of Derivative and Other Financial Instruments - Maturities of Debt Securities (Details) - PNMR and PNM $ in Thousands	Sep. 30, 2020 USD ($)
Available-for-Sale
Within 1 year	$ 29,941
After 1 year through 5 years	85,926
After 5 years through 10 years	85,507
After 10 years through 15 years	15,533
After 15 years through 20 years	8,861
After 20 years	41,289
Available-for-sale debt securities	$ 267,057

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

+ References

No definition available.

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

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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