Name:	psco_PublicUtilitiesAdjustmentRequestedByThirdPartiesRelatedToReturnOnEquityAndCapitalStructureAdjustments
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties related to the challenge of known and measurable changes in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToChallengeOfKnownAndMeasurable
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties related to elimination of certain incentive compensation in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToEliminationOfCertainIncentiveCompensation
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties related to elimination of depreciation annualization in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToEliminationOfDepreciationAnnualization
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of net disallowance requested by third parties for adjustments and corrections in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToNetDisallowanceForAdjustmentsAndCorrections
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties related to reduced recovery for other costs in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToOtherCosts
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties related to the removal of pension asset in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToRemovalOfPensionAsset
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties related to revenue adjustments in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToRevenueAdjustments
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of adjustment requested by third parties to move to a 13-month average from year-end rate base in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesAdjustmentToRequestedRateIncreaseDecreaseRequestedByThirdPartiesRelatedToUseOf13MonthAverageFromYearEndRateBase
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The cumulative amount of the customers' share of Renewable Energy Credit trading margins netted against the public utility's renewable energy standard adjustment (RESA) regulatory asset balance.

No definition available.

Name:	psco_PublicUtilitiesCumulativeCreditAgainstResaRegulatoryAssetBalance
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of the customers' share of Renewable Energy Credit trading margins netted against the public utility's renewable energy standard adjustment (RESA) regulatory asset balance.

No definition available.

Name:	psco_PublicUtilitiesCustomersShareOfMarginsCreditedAgainstResaRegulatoryAssetBalance
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The percentage of equity to capital, including debt and equity, recommended by third parties in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesEquityCapitalStructureRecommendedByThirdParties
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The public utility's percentage of margin associated with stand-alone Renewable Energy Credit (REC) transactions which will be shared beginning in 2011 as determined by regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesInitialPercentageOfMarginAssociatedWithStandAloneRecTransactions
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The public utility's margin threshold which determines the percentage of margin sharing related to hybrid Renewable Energy Credit (REC) trades. Margins less than $20 million on hybrid REC trades of are shared 80 percent to the customers and 20 percent to the public utility. Margins in excess of the $20 million are to be shared 90 percent to the customers and 10 percent to the public utility.

No definition available.

Name:	psco_PublicUtilitiesMarginThresholdDeterminingPercentageOfMarginSharing
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The number of intervenors who filed testimony in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesNumberOfIntervenorsFilingTestimony
Namespace Prefix:	psco_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The public utility's percentage of margin associated with Colorado Renewable Energy Credits (REC) approved to be shared on the first $20 million of margins on hybrid REC trades.

No definition available.

Name:	psco_PublicUtilitiesPercentageOfMarginOnHybridRecApprovedForFirst20MillionOfMargins
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The public utility's percentage of margin associated with Colorado Renewable Energy Credits (REC) approved to be shared in excess of $20 million of margins on hybrid REC trades.

No definition available.

Name:	psco_PublicUtilitiesPercentageOfMarginOnHybridRecApprovedForMarginsInExcessOf20Million
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount of the rate increase (decrease) recommended by third parties in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesRateIncreaseDecreaseRecommendedByThirdParties
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	psco_PublicUtilitiesRateMattersAbstract
Namespace Prefix:	psco_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Percentage of public utility's requested equity to capital, including debt and equity.

No definition available.

Name:	psco_PublicUtilitiesRequestedEquityCapitalStructurePercentage
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount of public utility's rate base in the filing with regulatory agency on which the public utility is allowed to earn a particular rate of return.

No definition available.

Name:	psco_PublicUtilitiesRequestedRateBaseAmount
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of public utility's amended requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesRequestedRateIncreaseDecreaseAmendedAmount
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Percentage of public utility's requested return on equity.

No definition available.

Name:	psco_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The rate of return on equity recommended by third parties in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesReturnOnEquityRecommendedByThirdParties
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The return on equity used in the public utility's earnings test approved by regulatory agency in which customers and shareholders will share weather normalized earnings.

No definition available.

Name:	psco_PublicUtilitiesReturnOnEquityUsedInWeatherNormalizedEarningsTest
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Tax impact related to adjustments requested by third parties in the public utility's requested rate increase (decrease) with regulatory agency.

No definition available.

Name:	psco_PublicUtilitiesTaxImpactOfAdjustmentsToRequestedRateIncreaseDecreaseRequestedByThirdParties
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The public utility's ultimate percentage of margin associated with stand-alone Renewable Energy Credit (REC) transactions which will be shared by 2014 as determined by regulatory agency.

No definition available.