Fair Value of Derivative and Other Financial Instruments - Margin, Notional Amounts and Credit Rating (Details)	3 Months Ended	12 Months Ended
Mar. 31, 2020 USD ($) MMBTU	Dec. 31, 2019 USD ($) MMBTU
Derivative [Line Items]
Contract in a liability position \| $	$ 0	$ 0
PNM \| Commodity derivatives \| Fair value hedging
Derivative [Line Items]
Economic Hedges (in mmbtu and mwh) \| MMBTU	0	0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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