Debt Instrument, Covenant, Debt-to-Capital Ratio

No definition available.

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- Definition

Debt Instrument, Number of Loans

+ References

No definition available.

+ Details

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- Definition

Debt Instrument, Shelf Registration Statement for Unsecured Debt

+ References

No definition available.

+ Details

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- Definition

Payments to fund long-term loans to unaffiliated third party

+ References

No definition available.

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- Definition

Public Utilities, Requirement to Obtain Approval for Financing Transactions, Minimum Maturity

+ References

No definition available.

+ Details

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- Definition

Ratio of debt to capital, maximum

+ References

No definition available.

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- Definition

Term loan restatement committed amount

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Term loan restatement to provide additional funding

+ References

No definition available.

+ Details

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- Definition

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

+ References

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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

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Period Type:	instant

- Definition

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

+ References

+ 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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- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- 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

Carrying amount as of the balance sheet date of unearned revenue or income, not otherwise specified in the taxonomy, which is expected to be taken into income after one year or beyond the normal operating cycle, if longer and noncurrent obligations not separately disclosed in the balance sheet (other liabilities, noncurrent).

+ References

No definition available.

+ Details

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

- 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

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- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

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+ 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.

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- 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.

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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

The cash inflow from a borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

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- Definition

Amount of transactions with related party during the financial reporting period.

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- Definition

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

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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

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 - Activities, PNM and TNMP (Details)											1 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended
Financing - Activities, PNM and TNMP (Details)	Jan. 18, 2019 USD ($)	Dec. 21, 2018 USD ($)	Dec. 14, 2018 USD ($)	Nov. 26, 2018 USD ($)	Jul. 31, 2018 USD ($)	May 14, 2018 USD ($)	Apr. 09, 2018 USD ($)	Jul. 28, 2017 USD ($)	Feb. 01, 2016 USD ($)	Dec. 21, 2015 USD ($)	Jul. 31, 2018 USD ($)	Jun. 21, 2016 USD ($)	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2018 USD ($) derivative	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 29, 2019 USD ($)	Feb. 26, 2019 USD ($)	Feb. 22, 2019	Dec. 17, 2018 USD ($)	Jul. 25, 2018 USD ($)	Jun. 28, 2018 USD ($)	May 22, 2018 USD ($)	Mar. 09, 2018 USD ($)	Jul. 20, 2017 USD ($)	Jun. 14, 2017 USD ($)	Dec. 21, 2016 USD ($) loan	Oct. 21, 2016 USD ($)	Sep. 27, 2016 USD ($)	May 20, 2016 USD ($)	Jan. 01, 2016 USD ($)	Dec. 17, 2015 USD ($)	Sep. 30, 2015	Mar. 09, 2015 USD ($)
Debt Instrument [Line Items]
Amount outstanding															$ 50,000,000	$ 0	$ 100,000,000
Outstanding amount															235,900,000	305,400,000
Interest charges															127,244,000	127,625,000	128,633,000
Other deferred credits															165,157,000	131,706,000
Fixed interest rate																																		1.927%
PNMR 2016 One-Year Term Loan and PNMR 2016 Two-Year Term Loan
Debt Instrument [Line Items]
Number of loan agreements (in loans) \| loan																												2
PNMR 2016 One Year Term Loan
Debt Instrument [Line Items]
Outstanding amount															$ 150,000,000	100,000,000												$ 100,000,000.0
Debt instrument, term											1 year
PNMR 2016 Two-Year Term Loan due December 2018
Debt Instrument [Line Items]
Loan entered into																												100,000,000.0
Debt instrument, term											2 years
PNMR Development Term Loan due November 2020
Debt Instrument [Line Items]
Outstanding amount				$ 90,000,000
PNMR 2018 One Year Term Loan
Debt Instrument [Line Items]
Aggregate principal amount			$ 150,000,000
Debt instrument, term			1 year
Variable interest rate															3.20%
PNMR 2018 Two-Year Term Loan due December 2020
Debt Instrument [Line Items]
Aggregate principal amount		$ 50,000,000
Debt instrument, term		2 years
Variable interest rate															3.28%
TNMP 2018 Term Loan Agreement
Debt Instrument [Line Items]
Term loan restatement to provide additional funding																					$ 15,000,000
TNMP 2018 Term Loan due July 2020
Debt Instrument [Line Items]
Variable interest rate															3.22%
Term loan restatement committed amount																					$ 35,000,000
Variable Rate Short-Term Debt
Debt Instrument [Line Items]
Aggregate principal amount															$ 50,000,000.0
Time hedged in interest rate cash flow hedge															4 years
Level 2 \| Cash Flow Hedging
Debt Instrument [Line Items]
Fair value gain (loss, less than)															$ 1,000,000	1,400,000
NM Capital \| San Juan Generating Station \| Coal Supply
Debt Instrument [Line Items]
Payments to fund long-term loans to unaffiliated third party									$ 125,000,000
NM Capital \| San Juan Coal Company, Westmoreland \| Coal Supply
Debt Instrument [Line Items]
Repurchased face amount																								$ 50,100,000
PNMR \| PNMR 2016 Two-Year Term Loan due December 2018
Debt Instrument [Line Items]
Loan entered into															0	100,000,000
PNMR \| PNMR Development Term Loan due November 2020
Debt Instrument [Line Items]
Loan entered into															90,000,000	0
PNMR \| PNMR 2018 Two-Year Term Loan due December 2020
Debt Instrument [Line Items]
Loan entered into															50,000,000	0
Public Service Company of New Mexico
Debt Instrument [Line Items]
Outstanding amount															42,400,000	39,800,000
Interest charges															76,458,000	82,697,000	87,469,000
Other deferred credits															$ 213,226,000	106,442,000
Public Service Company of New Mexico \| NMPRC
Debt Instrument [Line Items]
Requirement to obtain approval for any financing transaction, period of time (more than)															18 months
PNM \| PNM 2019 Term Loan \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount	$ 250,000,000.0
Texas-New Mexico Power Company
Debt Instrument [Line Items]
Outstanding amount															$ 17,500,000	0
Interest charges															32,091,000	30,084,000	$ 29,335,000
Other deferred credits															$ 2,908,000	7,448,000
Line of Credit
Debt Instrument [Line Items]
Debt-to-capital ratios (less than or equal to)				3.32%							70.00%		65.00%	65.00%	70.00%
Line of Credit \| Public Service Company of New Mexico
Debt Instrument [Line Items]
Debt-to-capital ratios (less than or equal to)															65.00%
Line of Credit \| Texas-New Mexico Power Company
Debt Instrument [Line Items]
Debt-to-capital ratios (less than or equal to)															65.00%
PNMR 2015 Term Loan Agreement
Debt Instrument [Line Items]
Loan entered into																												$ 150,000,000.0							$ 150,000,000.0
BTMU Term Loan Agreement \| NM Capital
Debt Instrument [Line Items]
Loan entered into									$ 125,000,000.0
Repurchased face amount																								$ 43,000,000
Estimated principal payments															$ 43,000,000
Letter of Credit \| PNMR \| Letter or credit, 30 mil JP Morgan
Debt Instrument [Line Items]
Aggregate principal amount																													$ 30,300,000.0
Senior Unsecured Notes
Debt Instrument [Line Items]
Aggregate principal amount																									$ 300,000,000.0
Stated percentage																									3.25%
Senior Unsecured Notes \| Public Service Company of New Mexico \| Senior Unsecured Note Agreement (SUNs)
Debt Instrument [Line Items]
Aggregate principal amount								$ 450,000,000.0
Debt to capital ratio								65.00%
PNM 2014 Multi-Draw Term Loan Agreement \| Public Service Company of New Mexico
Debt Instrument [Line Items]
Loan entered into																																$ 125,000,000
Repayments of debt												$ 125,000,000.0
PNM 2016 Term Loan Agreement due 2017 \| Public Service Company of New Mexico
Debt Instrument [Line Items]
Aggregate principal amount																															$ 175,000,000.0
Pollution Control Bonds \| Public Service Company of New Mexico \| Pollution Control Revenue Bonds 1 Point 875 Percent, due 2021
Debt Instrument [Line Items]
Aggregate principal amount																														$ 146,000,000.0
Stated percentage																														1.875%
Pollution Control Bonds \| Public Service Company of New Mexico \| Pollution Control Revenue Bonds 2.125 Percent, due 2040
Debt Instrument [Line Items]
Aggregate principal amount																																$ 37,000,000.0
Stated percentage																																2.125%
Pollution Control Bonds \| Public Service Company of New Mexico \| Pollution Control Revenue Bonds 2.45 Percent, due 2042
Debt Instrument [Line Items]
Aggregate principal amount																																$ 20,000,000.0
Stated percentage																																2.45%
Unsecured Debt \| Public Service Company of New Mexico
Debt Instrument [Line Items]
Shelf registration statement, capacity of issuance (up to)															475,000,000
Unsecured Debt \| Public Service Company of New Mexico \| PNM 2017 Term Loan Agreement
Debt Instrument [Line Items]
Loan entered into															$ 200,000,000	$ 200,000,000
Unsecured Debt \| Public Service Company of New Mexico \| SUNs, Issuance in May 2018 \| Minimum
Debt Instrument [Line Items]
Stated percentage						3.15%
Debt instrument, term						5 years
Unsecured Debt \| Public Service Company of New Mexico \| SUNs, Issuance in May 2018 \| Maximum
Debt Instrument [Line Items]
Stated percentage						4.50%
Debt instrument, term						30 years
Unsecured Debt \| Public Service Company of New Mexico \| SUN's, Issuance in July 2018 \| Minimum
Debt Instrument [Line Items]
Stated percentage					3.78%						3.78%
Debt instrument, term					10 years
Unsecured Debt \| Public Service Company of New Mexico \| SUN's, Issuance in July 2018 \| Maximum
Debt Instrument [Line Items]
Stated percentage					4.60%						4.60%
Debt instrument, term					30 years
Unsecured Debt \| Public Service Company of New Mexico \| 7.95% due May 2018
Debt Instrument [Line Items]
Stated percentage						7.95%
Unsecured Debt \| Public Service Company of New Mexico \| 7.50% due August 2018
Debt Instrument [Line Items]
Stated percentage					7.50%						7.50%
Unsecured Debt \| Texas-New Mexico Power Company \| 9.50% due April 2019 \| Subsequent Event
Debt Instrument [Line Items]
Stated percentage	9.50%
Extinguishment of debt	$ 172,300,000
First Mortgage Bonds \| Texas-New Mexico Power Company \| 3.53% due February 2026
Debt Instrument [Line Items]
Aggregate principal amount																																	$ 60,000,000.0
Stated percentage															3.53%	3.53%																	3.53%
First Mortgage Bonds \| Texas-New Mexico Power Company \| TNMP 2018 Term Loan due July 2020
Debt Instrument [Line Items]
Loan entered into															$ 35,000,000	$ 0
First Mortgage Bonds \| Texas-New Mexico Power Company \| 9.50% due April 2019
Debt Instrument [Line Items]
Stated percentage															9.50%	9.50%
Mortgages \| Texas-New Mexico Power Company \| First Mortgage Bonds
Debt Instrument [Line Items]
Aggregate principal amount																							$ 60,000,000.0
Stated percentage																							3.85%
Mortgages \| Texas-New Mexico Power Company \| TNMP 2019 Bond Purchase Agreement \| Subsequent Event
Debt Instrument [Line Items]
Aggregate principal amount																		$ 225,000,000	$ 305,000,000.0
Stated percentage																			400.00%
Debt to capital ratio	65.00%
Secured Debt \| Texas-New Mexico Power Company \| TNMP Term Loan Agreement
Debt Instrument [Line Items]
Aggregate principal amount																						$ 20,000,000.0
JPMorgan Chase Bank, N.A. and U.S. Bank National Association \| PNM 2016 Term Loan Agreement due 2017 \| Public Service Company of New Mexico
Debt Instrument [Line Items]
Aggregate principal amount																$ 175,000,000.0
JPMorgan Chase Bank, N.A. and U.S. Bank National Association \| Notes Payable to Banks \| Public Service Company of New Mexico \| PNM 2017 Term Loan Agreement
Debt Instrument [Line Items]
Aggregate principal amount																										$ 200,000,000.0
Stated percentage															3.26%
JPMorgan Chase Bank, N.A. and U.S. Bank National Association \| Notes Payable to Banks \| Public Service Company of New Mexico \| PNM 2019 Term Loan \| Subsequent Event
Debt Instrument [Line Items]
Stated percentage																				3.13%
Scenario, plan \| Senior Unsecured Notes \| Public Service Company of New Mexico \| SUNs, Issuance in May 2018
Debt Instrument [Line Items]
Aggregate principal amount						$ 350,000,000.0
Scenario, plan \| Senior Unsecured Notes \| Public Service Company of New Mexico \| SUN's, Issuance in July 2018
Debt Instrument [Line Items]
Aggregate principal amount					$ 100,000,000.0						$ 100,000,000.0
Scenario, plan \| First Mortgage Bonds \| Texas-New Mexico Power Company \| Interest Rate of 3.22%, Due 2027
Debt Instrument [Line Items]
Aggregate principal amount																											$ 60,000,000.0
Stated percentage																											3.22%
Interest rate contract
Debt Instrument [Line Items]
Number of derivative instruments held \| derivative															3
Interest rate contract one \| Variable Rate Short-Term Debt
Debt Instrument [Line Items]
Fixed interest rate															1.926%
Interest rate contract two \| Variable Rate Short-Term Debt
Debt Instrument [Line Items]
Fixed interest rate															1.823%
Interest rate contract three \| Variable Rate Short-Term Debt
Debt Instrument [Line Items]
Fixed interest rate															1.629%
Deposit Related To Potential Transmission Interconnections \| PNMR Development
Debt Instrument [Line Items]
Amount of related party transaction							$ 68,200,000
Interest charges															$ 2,400,000
Other deferred credits							$ 68,200,000
Notes Payable to Banks \| PNMR Term Loan Agreement
Debt Instrument [Line Items]
Amount outstanding										$ 150,000,000.0