Debt Instruments, NMPRC Approved credit facility

No definition available.

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- Definition

Lease term extension period

+ References

No definition available.

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- Definition

Number Of Extensions

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- Definition

Short Term Debt Due to Related Party

+ References

No definition available.

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- Definition

Amount of assets pledged to secure a debt instrument.

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-Publisher FASB
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- Definition

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

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- Definition

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

+ References

+ 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.

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

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- Definition

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

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ 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

+ Details

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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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.

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- Definition

Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

No definition available.

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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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.

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- Definition

Weighted average interest rate of short-term debt outstanding calculated at point in time.

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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.

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Financing - Short-term Debt and Liquidity (Details)		1 Months Ended	9 Months Ended	12 Months Ended
Financing - Short-term Debt and Liquidity (Details)	Sep. 26, 2018 Extension	Jul. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($) derivative	Nov. 01, 2020 USD ($)	Oct. 30, 2018 USD ($)	Jul. 25, 2018	Jun. 28, 2018 USD ($)	Mar. 09, 2018 USD ($)	Feb. 26, 2018 USD ($)	Jul. 20, 2017 USD ($)	Dec. 21, 2016 USD ($)
Short-term Debt [Line Items]
Short-term debt			$ 262,600,000	$ 305,400,000
Letters of credit outstanding			4,700,000
Senior Unsecured Notes
Short-term Debt [Line Items]
Debt issued									$ 300,000,000.0
Stated interest rate									3.25%
Subsequent event
Short-term Debt [Line Items]
Remaining borrowing capacity						$ 653,700,000
PNMR \| Subsequent event
Short-term Debt [Line Items]
Remaining borrowing capacity						168,800,000
Consolidated invested cash						900,000
PNMR Development Revolving Credit Facility
Short-term Debt [Line Items]
Short-term debt			24,500,000	0
PNMR 2016 One-Year Term Loan (as extended)
Short-term Debt [Line Items]
Short-term debt			$ 100,000,000	$ 100,000,000								$ 100,000,000.0
Weighted-average interest rate for short-term debt			3.02%
Term of loan		1 year	1 year
Variable Rate Short-Term Debt
Short-term Debt [Line Items]
Term of derivatives				4 years
Debt issued				$ 50,000,000.0
PNMR 2016 Two-Year Term Loan
Short-term Debt [Line Items]
Short-term debt												$ 100,000,000.0
Term of loan		2 years	2 years
PNMR Revolving Credit Facility
Short-term Debt [Line Items]
Financing capacity			$ 10,000,000.0
Number of extensions \| Extension	2
Lease term extension period	1 year
PNMR Revolving Credit Facility \| PNMR
Short-term Debt [Line Items]
Weighted-average interest rate for short-term debt			3.34%
PNMR Revolving Credit Facility \| Forecast
Short-term Debt [Line Items]
Financing capacity					$ 290,000,000.0
TNMP Revolving Credit Facility \| PNMR
Short-term Debt [Line Items]
Weighted-average interest rate for short-term debt			2.99%
PNMR Development Revolving Credit Facility \| PNMR
Short-term Debt [Line Items]
Weighted-average interest rate for short-term debt			3.07%
PNM
Short-term Debt [Line Items]
Short-term debt			$ 0	39,800,000
Letters of credit outstanding			2,500,000
PNM \| Subsequent event
Short-term Debt [Line Items]
Remaining borrowing capacity						397,500,000
Consolidated invested cash						55,300,000
PNM \| Lines of credit
Short-term Debt [Line Items]
NMPRC approved credit facility			40,000,000
Short-term debt			$ 0	0
PNM \| Lines of credit \| Subsequent event
Short-term Debt [Line Items]
Remaining borrowing capacity						40,000,000
PNM \| SUNs, Issuance in August 2018 \| Senior Unsecured Notes
Short-term Debt [Line Items]
Debt issued		$ 100,000,000.0
PNM \| Senior Unsecured Notes, Due 2018, at 7 point 50 percent \| Unsecured debt
Short-term Debt [Line Items]
Stated interest rate			7.50%
PNM \| Plan \| SUNs, Issuance in August 2018 \| Senior Unsecured Notes
Short-term Debt [Line Items]
Debt issued			$ 100,000,000
PNM \| PNM Revolving Credit Facility
Short-term Debt [Line Items]
Financing capacity			40,000,000.0
PNM \| PNM Revolving Credit Facility \| Forecast
Short-term Debt [Line Items]
Financing capacity					$ 360,000,000.0
TNMP
Short-term Debt [Line Items]
Short-term debt			17,500,000	0
Letters of credit outstanding			100,000
Short-term debt – affiliate			4,100,000	0
TNMP \| Subsequent event
Short-term Debt [Line Items]
Remaining borrowing capacity						47,400,000
Consolidated invested cash						0
TNMP \| First Mortgage Bonds \| Mortgages
Short-term Debt [Line Items]
Debt issued			172,300,000.0					$ 60,000,000.0
Stated interest rate							2.94%	3.85%
PNMR Development \| Subsequent event
Short-term Debt [Line Items]
Remaining borrowing capacity						0
PNMR Development \| PNMR 2018 Revolving Credit Facility
Short-term Debt [Line Items]
Financing capacity										$ 24,500,000.0
Revolving credit facility
Short-term Debt [Line Items]
Financing capacity			300,000,000.0
Short-term debt			120,600,000	165,600,000
Revolving credit facility \| PNM
Short-term Debt [Line Items]
Financing capacity			400,000,000.0
Short-term debt			0	39,800,000
Revolving credit facility \| TNMP
Short-term Debt [Line Items]
Financing capacity			75,000,000.0
Short-term debt			17,500,000	$ 0
Revolving credit facility \| TNMP \| First mortgage bonds
Short-term Debt [Line Items]
Collateral amount			75,000,000
Affiliated entity \| PNM \| Subsequent event
Short-term Debt [Line Items]
Short-term debt – affiliate						0
Affiliated entity \| TNMP \| Subsequent event
Short-term Debt [Line Items]
Short-term debt – affiliate						$ 5,400,000.0
Interest rate contract
Short-term Debt [Line Items]
Number of derivatives \| derivative				3
Interest rate 1 \| Variable Rate Short-Term Debt
Short-term Debt [Line Items]
Fixed interest rate				1.926%
Interest rate 2 \| Variable Rate Short-Term Debt
Short-term Debt [Line Items]
Fixed interest rate				1.823%
Interest rate 3 \| Variable Rate Short-Term Debt
Short-term Debt [Line Items]
Fixed interest rate				1.629%
Interest rate 3 \| Level 2 \| Cash Flow Hedge
Short-term Debt [Line Items]
Fair value gain (loss)			$ 4,000,000	$ 1,400,000
JPMorgan Chase Bank, N.A. and U.S. Bank National Association \| PNM \| PNM 2017 Term Loan Agreement \| Term loan agreement with banks
Short-term Debt [Line Items]
Debt issued											$ 200,000,000.0