Annual lease payments

No definition available.

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

- Definition

Cash received back from lessor

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Leasehold improvements, net book value

+ References

No definition available.

+ Details

Name:	pnm_LeaseholdImprovementsNetBookValue
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of obligated payments

+ References

No definition available.

+ Details

Name:	pnm_NumberOfObligatedPayments
Namespace Prefix:	pnm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Lease, Extended Term

+ References

No definition available.

+ Details

Name:	pnm_OperatingLeaseExtendedTerm
Namespace Prefix:	pnm_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases, Renewal Options After Original Lease Term

+ References

No definition available.

+ Details

Name:	pnm_OperatingLeasesRenewalOptionsAfterOriginalLeaseTerm
Namespace Prefix:	pnm_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases, Rental Expense, Obligated to pay taxes, insurance, utilities, and maintenance costs applicable to the building,

+ References

No definition available.

+ Details

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

- Definition

Operating Leases, Rental Expense, Obligated to pay taxes, insurance, utilities, and maintenance costs applicable to the building, allocation percentage

+ References

No definition available.

+ Details

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

- Definition

Operating Leases Rent Expense Return on Lessor notes Rental Payments to be Received

+ References

No definition available.

+ Details

Name:	pnm_OperatingLeasesRentExpenseReturnOnLessorNotesRentalPaymentsToBeReceived
Namespace Prefix:	pnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 14

-Paragraph 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossPortionNotAccrued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_OperatingLeasedAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The yearly payments due under the lease entered into in connection with the transaction involving the sale of property to another party and the lease of the property back to the seller.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6456341&loc=d3e50796-112755

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 16

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 98

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6452660&loc=d3e36991-112694

+ Details

Name:	us-gaap_SaleLeasebackTransactionAnnualRentalPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Lease Commitments Narratives (Details) (USD $)	12 Months Ended
Lease Commitments Narratives (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Lease commitments
Operating Lease, Extended term	6 years
Operating Leases, renewal options after original lease term	2 years
Public Service Company of New Mexico [Member]
Lease commitments
Operating Leases, renewal options after original lease term	2
Operating Leases, Rent Expense, Net	$ 78,422,000	$ 71,209,000	$ 75,865,000
Cash received back from lessor	55,600,000	56,300,000	55,000,000
Public Service Company of New Mexico [Member] \| Palo Verde Nuclear Generating Station [Member]
Lease commitments
Rental Payments, Fixed renewal option period during original terms of leases	50.00%
Loss contingency, range of possible loss, portion not accrued	178,300,000
Lease covenant	5.00%
Public Service Company of New Mexico [Member] \| Palo Verde Nuclear Generating Station, Unit 1 Leases [Member]
Lease commitments
Annual lease payments	33,000,000
Public Service Company of New Mexico [Member] \| Palo Verde Nuclear Generating Station, Unit 2 Leases [Member]
Lease commitments
Annual lease payments	23,700,000
Public Service Company of New Mexico [Member] \| Palo Verde Nuclear Generating Station and EIP [Member]
Lease commitments
Sale Leaseback Transaction, Annual Rental Payments	69,100,000
Public Service Company of New Mexico [Member] \| Navajo Nation [Member]
Lease commitments
Number of obligated payments	20
Annual lease payments	6,000,000
Public Service Company of New Mexico [Member] \| Delta [Member]
Lease commitments
Annual lease payments	6,000,000
Texas-New Mexico Power Company [Member]
Lease commitments
Operating Leases, Rent Expense, Net	3,606,000	3,737,000	2,493,000
Between PNM and Other Subsidiaries [Member] \| Public Service Company of New Mexico [Member] \| Palo Verde Nuclear Generating Station [Member]
Lease commitments
Operating Leases, Rent Expense			5,400,000
Corporate Headquarters [Member]
Lease commitments
Operating Leases, Rent Expense, Net	1,900,000
Operating Leases, Rental Expense, Obligated to pay taxes, insurance, utilities, and maintenance costs applicable to the building	1,000,000
Leasehold improvements, net book value	4,600,000
Corporate Headquarters [Member] \| Public Service Company of New Mexico [Member]
Lease commitments
Operating Leases, Rental Expense, Obligated to pay taxes, insurance, utilities, and maintenance costs applicable to the building, allocation percentage	85.00%
Corporate Headquarters [Member] \| Texas-New Mexico Power Company [Member]
Lease commitments
Operating Leases, Rental Expense, Obligated to pay taxes, insurance, utilities, and maintenance costs applicable to the building, allocation percentage	15.00%
Approximate Annual Total for Operating Lease Payments [Member]
Lease commitments
Operating Leases Rent Expense Return on Lessor notes Rental Payments to be Received	44,000,000
Approximate Annual Total for Operating Lease Payments [Member]
Lease commitments
Operating Leases Rent Expense Return on Lessor notes Rental Payments to be Received	$ 33,000,000