Debt Instrument, Covenant, Debt-to-Capital Ratio

No definition available.

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- Definition

Payments to fund long-term loans to unaffiliated third party

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Public Utilities, Maturity term over which financings require regulator approval

+ References

No definition available.

+ Details

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- Definition

Ratio of debt to capital, maximum

+ References

No definition available.

+ Details

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Data Type:	xbrli:monetaryItemType
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

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

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Balance Type:	na
Period Type:	instant

- 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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Period Type:	duration

- 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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Period Type:	duration

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959

+ Details

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- Definition

Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.

+ References

No definition available.

+ Details

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- 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/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

+ Details

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- Definition

Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

+ Details

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- Definition

Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

+ Details

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Financing - Financing Activities (Details)				6 Months Ended	12 Months Ended
Financing - Financing Activities (Details)	Jul. 28, 2017 USD ($)	Jul. 20, 2017 USD ($)	Feb. 01, 2016 USD ($)	Jun. 30, 2017 USD ($) derivative	Dec. 31, 2016 USD ($)	Jun. 14, 2017 USD ($)	Oct. 21, 2016 USD ($)	Sep. 30, 2015	Mar. 09, 2015 USD ($)
Debt Instrument [Line Items]
Fixed interest rate								1.927%
Estimated principal payments				$ 274,800,000
Interest rate contract
Debt Instrument [Line Items]
Number of hedging agreements (in derivatives) \| derivative				3
PNMR 2015 Term Loan Agreement
Debt Instrument [Line Items]
Interest rate at period end				2.00%
PNMR 2016 Two-Year Term Loan
Debt Instrument [Line Items]
Term loans				$ 100,000,000.0
Term of loan				2 years
Variable interest rate				2.17%
Variable rate short-term debt
Debt Instrument [Line Items]
Aggregate principal amount				$ 50,000,000.0
Term of hedging agreement				4 years
Variable rate short-term debt \| Interest rate contract, 1
Debt Instrument [Line Items]
Fixed interest rate				1.926%
Variable rate short-term debt \| Interest rate contract, 2
Debt Instrument [Line Items]
Fixed interest rate				1.823%
Variable rate short-term debt \| Interest rate contract, 3
Debt Instrument [Line Items]
Fixed interest rate				1.629%
Cash flow hedge \| Level 2
Debt Instrument [Line Items]
Fair value gain (loss) (less than)				$ 300,000	$ (100,000)
Cash flow hedge \| Level 2 \| Interest rate contract, 3
Debt Instrument [Line Items]
Fair value gain (loss) (less than)				200,000
Cash flow hedge \| Level 2 \| Interest rate contracts, 1 and 2
Debt Instrument [Line Items]
Fair value gain (loss) (less than)				$ (500,000)
PNM \| Maximum
Debt Instrument [Line Items]
Maturity term over which financings require regulator approval (more than)				18 months
NM Capital \| Coal supply \| San Juan Coal Company, Westmoreland
Debt Instrument [Line Items]
Payments to fund long-term loans to unaffiliated third party			$ 125,000,000.0
Line of credit
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)				65.00%
PNMR 2015 Term Loan Agreement
Debt Instrument [Line Items]
Term loans									$ 150,000,000.0
PNM 2016 Term Loan Agreement \| PNM
Debt Instrument [Line Items]
Aggregate principal amount				$ 175,000,000.0
Variable interest rate				1.83%
PNM 2016 Term Loan Agreement \| PNM \| JPMorgan Chase Bank, N.A. and U.S. Bank National Association
Debt Instrument [Line Items]
Aggregate principal amount					175,000,000.0
BTMU Term Loan Agreement \| NM Capital
Debt Instrument [Line Items]
Term loans			$ 125,000,000.0	$ 71,800,000
Stated interest rate				3.92%
Estimated principal payments				$ 24,800,000
Letter of credit \| PNMR \| JPM LOC Facility
Debt Instrument [Line Items]
Aggregate principal amount							$ 30,300,000.0
First mortgage bonds \| TNMP \| Interest Rate of 3.22%, Due 2027 \| Plan
Debt Instrument [Line Items]
Aggregate principal amount						$ 60,000,000.0
Stated interest rate						3.22%
Pollution Control Revenue Bonds \| PNM \| Pollution Control Revenue Bonds due June 1, 2040
Debt Instrument [Line Items]
Stated interest rate				2.125%
Outstanding balance				$ 37,000,000	37,000,000
Pollution Control Revenue Bonds \| PNM \| Pollution Control Revenue Bonds due June 1, 2042
Debt Instrument [Line Items]
Stated interest rate				2.45%
Outstanding balance				$ 20,000,000	$ 20,000,000
Term loan agreement with banks \| PNM \| PNM 2017 Term Loan Agreement \| JPMorgan Chase Bank, N.A. and U.S. Bank National Association \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount		$ 200,000,000
Covenant that requires the maintenance of a debt-to-capital ratio (less than or equal to)		65.00%
Senior Unsecured Notes \| PNM \| Senior Unsecured Note Agreement (SUNs) \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 450,000,000.0
Covenant that requires the maintenance of a debt-to-capital ratio (less than or equal to)	65.00%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018 \| Plan \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 350,000,000
Senior Unsecured Notes \| PNM \| SUNs, Issuance in August 2018 \| Plan \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	100,000,000
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018, Interest rate of 3.15% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 55,000,000
Stated interest rate	3.15%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018, Interest rate of 3.45% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 104,000,000
Stated interest rate	3.45%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018, Interest rate of 3.68% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 88,000,000
Stated interest rate	3.68%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018, Interest rate of 3.93% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 38,000,000
Stated interest rate	3.93%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018, Interest rate of 4.22% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 45,000,000
Stated interest rate	4.22%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in May 2018, Interest rate of 4.50% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 20,000,000
Stated interest rate	4.50%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in August 2018, Interest rate of 3.78% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 15,000,000
Stated interest rate	3.78%
Senior Unsecured Notes \| PNM \| SUNs, Issuance in August 2018, Interest rate of 4.60% \| Subsequent event
Debt Instrument [Line Items]
Aggregate principal amount	$ 85,000,000
Stated interest rate	4.60%
Unsecured debt \| PNM \| Senior Unsecured Notes, Maturity in May 2018, 7.95%
Debt Instrument [Line Items]
Stated interest rate				7.95%
Senior Unsecured Notes				$ 350,000,000.0
Unsecured debt \| PNM \| Senior Unsecured Notes, Maturity in August 2018, 7.50%
Debt Instrument [Line Items]
Stated interest rate				7.50%
Senior Unsecured Notes				$ 100,000,000.0