Additional Leased Capacity to be Purchased

No definition available.

Name:	pnm_AdditionalLeasedCapacitytobePurchased
Namespace Prefix:	pnm_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Annual lease payments

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Annual Lease Payments During Renewal Period

+ References

No definition available.

+ Details

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

- Definition

Lease Covenant, Restriction on Conveying, Transferring, Leasing, & Dividends

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Leased Capacity to be Purchased

+ References

No definition available.

+ Details

Name:	pnm_LeasedCapacitytobePurchased
Namespace Prefix:	pnm_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Non Contractual Operating Lease, Future Minimum Payments Due

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Lease, Extended Term

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases, Number of leases set to expire

+ References

No definition available.

+ Details

Name:	pnm_OperatingLeasesNumberofleasessettoexpire
Namespace Prefix:	pnm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Operating Leases, Period to expiration of the lease

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases, Renewal Options After Original Lease Term

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases of Lessee, Number of Leases

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Operating Leases of Lessee, Number of Lessors

+ References

No definition available.

+ Details

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Namespace Prefix:	pnm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Purchase Price of Leased Asset

+ References

No definition available.

+ Details

Name:	pnm_PurchasePriceofLeasedAsset
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Rental Payments, Fixed renewal option period during original terms of leases

+ References

No definition available.

+ Details

Name:	pnm_RentalPaymentsFixedRenewalOptionPeriodDuringOriginalTermsOfLeases
Namespace Prefix:	pnm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Right-Of-Way Lease Payments

+ References

No definition available.

+ Details

Name:	pnm_RightOfWayLeasePayments
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 05
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99385795&loc=d3e12631-108344

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Period Type:

- 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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Lease Commitments - Narrative (Details) $ in Millions		1 Months Ended	12 Months Ended
Lease Commitments - Narrative (Details) $ in Millions	Jan. 15, 2016 USD ($) lease MW	Apr. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) lease lessor	Jan. 15, 2015 lease	Dec. 31, 1986 lease	Dec. 31, 1985 lease
Lease commitments
Operating lease, option term extensions			2 years
Operating leases, renewal options after original lease term			6 years
PNMR
Lease commitments
Non contractual operating lease, future minimum payments due			$ 18.5
Public Service Company of New Mexico
Lease commitments
Non contractual operating lease, future minimum payments due			$ 7.5
Public Service Company of New Mexico \| Navajo Nation
Lease commitments
Number of operating leases set to expire \| lease			0
Operating leases, period to expiration of the lease			5 years
Annual lease payments			$ 6.0
Right-of-way lease payments		$ 6.9
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station
Lease commitments
Number of leases \| lease					4	4
Rental payments, fixed renewal option period during original terms of leases			50.00%
Lease covenants, restrictions on conveying, transferring, leasing, and dividends (more than)			5.00%
Loss contingency, range of possible loss, portion not accrued (up to)			$ 163.8
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 1 Leases
Lease commitments
Annual lease payments			33.0
Number of leases \| lease				4		4
Annual lease payments during renewal period			16.5
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 2 Leases
Lease commitments
Annual lease payments			$ 23.7
Number of leases \| lease	1		3		4
Annual lease payments during renewal period			$ 1.6
Estimated purchase price of leased asset	$ 78.1
Leased capacity to be purchased (in megawatts) \| MW	31.25
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 1, Lease with Maximum Option Period Provision
Lease commitments
Number of lessors \| lessor			4
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 2, Lease with Maximum Option Period Provision
Lease commitments
Number of leases \| lease			1
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 1, Lease Expires in 2023
Lease commitments
Number of leases \| lease			4
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 2, Lease Expires in 2024
Lease commitments
Number of leases \| lease			1
Public Service Company of New Mexico \| Palo Verde Nuclear Generating Station, Unit 2 Leases 32.76 MW
Lease commitments
Number of leases \| lease	2
Estimated purchase price of leased asset	$ 85.2
Additional capacity to be leased (in megawatts) \| MW	32.76
Texas-New Mexico Power Company
Lease commitments
Non contractual operating lease, future minimum payments due			$ 11.0