-- None. No documentation exists for this element. --

No definition available.

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- Definition

Public Utilities, Amount of proposed changes would be recoverable

+ References

No definition available.

+ Details

Name:	sps_PublicUtilitiesAmountofproposedchangeswouldberecoverable
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Data Type:	xbrli:monetaryItemType
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- Definition

Public Utilities, Amount proposed changes would increase wholesale transmission revenues

+ References

No definition available.

+ Details

Name:	sps_PublicUtilitiesAmountproposedchangeswouldincreasewholesaletransmissionrevenues
Namespace Prefix:	sps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Public Utilities, Annual Transmission Revenue Requirement Increase (SPS)

+ References

No definition available.

+ Details

Name:	sps_PublicUtilitiesAnnualTransmissionRevenueRequirementIncreaseSPS
Namespace Prefix:	sps_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Public Utilities, Billed Charges For Transmission Service Upgrades

+ References

No definition available.

+ Details

Name:	sps_PublicUtilitiesBilledChargesForTransmissionServiceUpgrades
Namespace Prefix:	sps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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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

Name:	us-gaap_LossContingenciesLineItems
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Balance Type:	na
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- Details

Name:	dei_LegalEntityAxis=sps_SpsMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAgencyAxis=sps_SouthwestPowerPoolSPPMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=sps_SPPOpenAccessTransmissionTariffUpgradeCostsMember
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Commitments and Contingencies, Legal Contingencies (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Loss Contingencies [Line Items]
Public Utilities, Amount proposed changes would increase wholesale transmission revenues		$ 9.4
Legal Contingencies [Abstract]
Public Utilities, Amount of proposed changes would be recoverable		$ 4.4
SPS [Member] \| Southwest Power Pool (SPP) [Member] \| SPP Open Access Transmission Tariff Upgrade Costs [Member]
Loss Contingencies [Line Items]
Public Utilities, Billed Charges For Transmission Service Upgrades			$ 13.0
Legal Contingencies [Abstract]
Public Utilities, Annual Transmission Revenue Requirement Increase (SPS)	$ 6.0