Debt Instrument, Covenant, Debt To Capitalization Ratio

No definition available.

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- Definition

Debt Instrument, Prepayment Period

+ References

No definition available.

+ Details

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- Definition

Debt Instrument, Series Of Bond Issuance

+ References

No definition available.

+ Details

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- Definition

Public Utilities, Maturity term over which financings require regulator approval

+ References

No definition available.

+ Details

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- Definition

Public Utilities, Request Issuance Of Energy Transition Bonds

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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- Definition

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.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

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-Name Accounting Standards Codification
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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

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Financing - Financing Activities (Details)											9 Months Ended
Financing - Financing Activities (Details)	Oct. 20, 2020 USD ($)	Jun. 22, 2020 USD ($)	Apr. 30, 2020 USD ($)	Apr. 24, 2020 USD ($) bond_series	Apr. 15, 2020 USD ($)	Apr. 01, 2020 USD ($)	Jan. 08, 2020 $ / shares shares	Jan. 07, 2020 shares	Jan. 01, 2020	Jul. 01, 2019 USD ($)	Sep. 30, 2020 USD ($) shares	Oct. 27, 2020 USD ($)	Jul. 15, 2020 USD ($)	Jun. 01, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	Jul. 22, 2019 USD ($)	Jul. 21, 2019 USD ($)	Oct. 31, 2016 USD ($)
Debt Instrument [Line Items]
Common stock, shares issued (in shares) \| shares											79,653,624				79,653,624
Financing capacity																$ 50,000,000.0	$ 40,000,000.0
PNMR 2020 Forward Equity Sales Agreement
Debt Instrument [Line Items]
Common stock, shares issued (in shares) \| shares								6,200,000
Sale of stock, price per share (in dollars per share) \| $ / shares							$ 47.21
Over-Allotment Option
Debt Instrument [Line Items]
Number of shares issued in transaction (in shares) \| shares							800,000	800,000
PNMR 2018 Two Year Term Loan
Debt Instrument [Line Items]
Aggregate principal amount											$ 50,000,000.0
Variable interest rate											0.95%
Term loans											$ 50,000,000.0
Term of loan											2 years
PNMR 2019 Term Loan
Debt Instrument [Line Items]
Variable interest rate											1.11%
PNMR Development Term Loan
Debt Instrument [Line Items]
Aggregate principal amount											$ 90,000,000.0
PNM
Debt Instrument [Line Items]
Common stock, shares issued (in shares) \| shares											39,117,799				39,117,799
PNM \| PNM 2019 40 Million Term Loan
Debt Instrument [Line Items]
Aggregate principal amount											$ 40,000,000.0
Variable interest rate											0.80%
PNM \| Maximum
Debt Instrument [Line Items]
Maturity term over which financings require regulator approval (more than)											18 months
PNMR \| Merger Backstop Facilities \| Subsequent event
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)	70.00%
PNMR \| Merger Backstop Facilities \| Subsequent event \| Term Loan
Debt Instrument [Line Items]
Financing capacity	$ 50,000,000.0
Term of loan	364 days
PNMR \| Merger Backstop Facilities \| Revolving credit facility \| Subsequent event \| Line of credit
Debt Instrument [Line Items]
Financing capacity	$ 300,000,000.0
Term of loan	364 days
Texas-New Mexico Power Company
Debt Instrument [Line Items]
Common stock, shares issued (in shares) \| shares											6,358				6,358
Line of credit \| PNMR and PNMR Development
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)											70.00%
Line of credit \| PNM and TNMP
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)											65.00%
Line of credit \| PNM \| PNM Revolving Credit Facility
Debt Instrument [Line Items]
Repayments of debt			$ 100,000,000.0
Letter of credit \| PNMR \| JPM LOC Facility
Debt Instrument [Line Items]
Aggregate principal amount																		$ 30,300,000
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)				65.00%
Aggregate principal amount				$ 185,000,000.0									$ 185,000,000.0
Series of bond issuance \| bond_series				4
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement, Bond Series 1 and 2
Debt Instrument [Line Items]
Aggregate principal amount				$ 110,000,000.0
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement, Bond Series 1
Debt Instrument [Line Items]
Aggregate principal amount				$ 85,000,000.0
Stated interest rate				2.73%
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement, Bond Series 2
Debt Instrument [Line Items]
Aggregate principal amount				$ 25,000,000.0
Stated interest rate				3.36%
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement, Bond Series 3 and 4
Debt Instrument [Line Items]
Aggregate principal amount													75,000,000.0
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement, Bond Series 3
Debt Instrument [Line Items]
Aggregate principal amount													$ 25,000,000.0
Stated interest rate													2.93%
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2020 Bond Purchase Agreement, Bond Series 4
Debt Instrument [Line Items]
Aggregate principal amount													$ 50,000,000.0
Stated interest rate													3.36%
Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP First Mortgage Bonds
Debt Instrument [Line Items]
Aggregate principal amount											$ 750,000,000.0
Debt instrument, prepayment period											30 days
Debt instrument, redemption price, percentage of principal amount redeemed											100.00%
Medium-term Notes \| PNM \| PNM 2020 250 Million Term Loan
Debt Instrument [Line Items]
Aggregate principal amount					$ 250,000,000.0
Variable interest rate											2.70%
Medium-term Notes \| PNM \| PNM 2019 Term Loan
Debt Instrument [Line Items]
Repayments of debt					$ 250,000,000.0
Senior Notes \| Senior Unsecured Notes, 3.21% Series A, due April 2030
Debt Instrument [Line Items]
Aggregate principal amount			$ 150,000,000.0
Stated interest rate			3.21%
Senior Notes \| Senior Unsecured Notes, 3.57% Series B, due April 2039
Debt Instrument [Line Items]
Aggregate principal amount			$ 50,000,000.0
Stated interest rate			3.57%
Senior Notes \| PNM
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)			65.00%
Aggregate principal amount			$ 200,000,000.0
Senior Notes \| PNM \| PNM 2020 250 Million Term Loan
Debt Instrument [Line Items]
Repayments of debt			$ 100,000,000.0
Bonds
Debt Instrument [Line Items]
Aggregate principal amount											$ 302,500,000
Repayments of debt		$ 302,500,000
Bonds \| City of Farmington, New Mexico
Debt Instrument [Line Items]
Aggregate principal amount														$ 266,500,000
Bonds \| Pollution Control Revenue Bonds
Debt Instrument [Line Items]
Stated interest rate											0.32%
Term loans															$ 100,300,000
Bonds \| Pollution Control Revenue Bonds \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount												$ 100,300,000
Bonds \| Pollution Control Revenue Bonds, Due 2040
Debt Instrument [Line Items]
Term loans															40,000,000.0
Bonds \| Pollution Control Revenue Bonds, Due 2043, Series 1
Debt Instrument [Line Items]
Term loans															39,300,000
Bonds \| Pollution Control Revenue Bonds, Due 2043, Series 2
Debt Instrument [Line Items]
Term loans															21,000,000.0
Bonds \| Pollution Control Revenue Bonds, 5.90%, Callable \| City of Farmington, New Mexico
Debt Instrument [Line Items]
Aggregate principal amount															$ 255,000,000.0
Stated interest rate															5.90%
Bonds \| Pollution Control Revenue Bonds, 6.25%, Callable \| Maricopa County, Arizona Pollution Control Corporation
Debt Instrument [Line Items]
Aggregate principal amount															$ 36,000,000.0
Stated interest rate															6.25%
Debt instrument, redemption price, percentage									101.00%
Bonds \| Pollution Control Revenue Bonds, 6.25%, Callable \| City of Farmington, New Mexico
Debt Instrument [Line Items]
Aggregate principal amount															$ 11,500,000
Stated interest rate															6.25%
Bonds \| Pollution Control Revenue Bonds, 1.05 Percent Due 2022
Debt Instrument [Line Items]
Aggregate principal amount											$ 36,000,000.0
Stated interest rate											1.05%
Bonds \| Pollution Control Revenue Bonds, 1.20 Percent Due 2022
Debt Instrument [Line Items]
Aggregate principal amount											$ 11,500,000
Stated interest rate											1.20%
Bonds \| Pollution Control Revenue Bonds, 1.10 Percent Due 2023
Debt Instrument [Line Items]
Aggregate principal amount											$ 130,000,000.0
Stated interest rate											1.10%
Bonds \| Pollution Control Revenue Bonds, 1.15 Percent Due 2024
Debt Instrument [Line Items]
Aggregate principal amount											$ 125,000,000.0
Stated interest rate											1.15%
Term loan agreement with banks \| PNM \| PNM 2020 250 Million Term Loan
Debt Instrument [Line Items]
Aggregate principal amount											$ 150,000,000.0
Term loan agreement with banks \| PNM \| PNM 2019 Term Loan
Debt Instrument [Line Items]
Aggregate principal amount											$ 150,000,000.0
Term loan agreement with banks \| PNM \| PNM 2020 Term Loan
Debt Instrument [Line Items]
Variable interest rate											2.70%
Term loan agreement with banks \| Texas-New Mexico Power Company \| PNMR Development Term Loan
Debt Instrument [Line Items]
Aggregate principal amount											$ 90,000,000.0
Variable interest rate											0.95%
San Juan Generating Station \| PNM
Debt Instrument [Line Items]
Request issuance of energy transition bonds						$ 361,000,000				$ 361,000,000