Long-term debt, required quarterly payment

No definition available.

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Period Type:	duration

- Definition

Payments to fund long-tern 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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Period Type:	duration

- Definition

Ratio of debt to capital, maximum

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- 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=34725769&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=6451184&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

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(a)(1))
-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 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. 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 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 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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=56946850&loc=SL5624171-113959

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Balance Type:	credit
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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Financing - Financing Activities (Details) - USD ($)		3 Months Ended		12 Months Ended
Financing - Financing Activities (Details) - USD ($)	Feb. 01, 2016	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 17, 2015	Sep. 30, 2015	Mar. 09, 2015
Debt Instrument [Line Items]
Fixed interest rate						1.927%
Cash Flow Hedging [Member] \| Fair Value, Inputs, Level 2 [Member]
Debt Instrument [Line Items]
Fair value gain (loss)			$ (1,100,000)	$ 100,000
NM Capital [Member] \| Coal Supply [Member] \| San Juan Generating Station [Member]
Debt Instrument [Line Items]
Payments to fund long-term loans to unaffiliated third party	$ 125,000,000.0
Maximum [Member] \| Public Service Company of New Mexico [Member]
Debt Instrument [Line Items]
Maturity term over which financings require regulator approval			18 months
Line of Credit [Member]
Debt Instrument [Line Items]
Ratio of debt to capital (less than or equal to)			65.00%
PNMR 2015 Term Loan Agreement [Member]
Debt Instrument [Line Items]
Term loans							$ 150,000,000.0
Interest rate			1.35%
BTMU Term Loan Agreement [Member] \| NM Capital [Member]
Debt Instrument [Line Items]
Term loans	$ 125,000,000.0
Stated interest rate			3.37%
First Mortgage Bonds [Member] \| Texas-New Mexico Power Company [Member] \| First Mortgage Bonds, 3.53%, due 2026, Series 2016A [Member]
Debt Instrument [Line Items]
Stated interest rate					3.53%
Aggregate principal amount					$ 60,000,000.0
PNM 2014 Multi-Draw Term Loan Agreement [Member] \| Public Service Company of New Mexico [Member]
Debt Instrument [Line Items]
Term loans			$ 125,000,000
Interest rate			1.02%
Subsequent Event [Member] \| BTMU Term Loan Agreement [Member] \| Minimum [Member] \| NM Capital [Member]
Debt Instrument [Line Items]
Long-term debt, required quarterly payment		$ 5,000,000.0