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Fair Value of Derivative and Other Financial Instruments - Effect of Mark-to-Market Instruments on Earnings (Details) - PNMR and PNM - Designated as hedging instrument - Commodity Contract - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss)	$ (102)	$ (235)	$ (1,261)
Electric operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss)	(50)	5,151	(53)
Cost of energy
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss)	$ (52)	$ (5,386)	$ (1,208)

X

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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+ References

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