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

The first range of an earnings test in the entity's rate regulatory proceeding approved for implementation, filed with the applicable regulatory agency, in which customers and shareholders will share weather normalized earnings above a rate of return on equity of 10.0%. The first range is greater than 10.0% and less than or equal to 10.2%.

No definition available.

Name:	psco_EarningsTestRoeRange1
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The second range of an earnings test in the entity's rate regulatory proceeding approved for implementation, filed with the applicable regulatory agency, in which customers and shareholders will share weather normalized earnings above a rate of return on equity of 10.0%. The second range is greater than 10.2% and less than or equal to 10.5%.

No definition available.

Name:	psco_EarningsTestRoeRange2
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The third range of an earnings test in the entity's rate regulatory proceeding approved for implementation, filed with the applicable regulatory agency, in which customers and shareholders will share weather normalized earnings above a rate of return on equity of 10.0%. The third range is greater than 10.5%.

No definition available.

Name:	psco_EarningsTestRoeRange3
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The adjustment to the entity's requested amount of increase (decrease) to existing rates related to depreciation expense, approved by the applicable regulatory agency.

No definition available.

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

The entity's amortization period for incremental property taxes that will have deferred accounting treatment approved for implementation by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysAmortizationPeriodForDeferredIncrementalPropertyTaxes
Namespace Prefix:	psco_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	instant

The ratio of equity to total capitalization (debt plus equity) used in the rate regulatory proceeding, approved by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysApprovedEquityRatioPercent
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Rate of return on equity that the entity's revenue increase requested represented through a rate case proceeding, approved by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysApprovedPercentReturnOnEquity
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's high end of the range of the rate of return on equity that the entity's revised revenue increase requested represented through a rate case proceeding for 2011, approved by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysApprovedPercentReturnOnEquityHighEndOfRange
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's low end of the range of the rate of return on equity that the entity's revised revenue increase requested represented through a rate case proceeding for 2011, approved by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysApprovedPercentReturnOnEquityLowEndOfRange
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's implemented interim rate increase (decrease) to existing rates, approved by the applicable regulatory agency.

No definition available.

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

The entity's minimum net revenue requirements increases (decreases) caused by changes in tax law, government mandates, or natural disasters which may be deferred or recovered through a modified rate adjustment, filed with the applicable regulatory agency.

No definition available.

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

The entity's minimum percent of normalized base revenues in either 2012 or 2013 below 2011 actual levels adjusted to reflect the rate increases allowed for 2012 and 2013 which give the entity the right to an additional rate adjustment in the next year for 50 percent of the shortfall, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysMinimumPercentOfNormalizedBaseRevenuesBelowAdjustedActualLevels
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The ratio of equity to total capitalization (debt plus equity) used in the entity's original requested rate regulatory proceeding, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysOriginalRequestedEquityRatioPercent
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Rate of return on equity that the entity's original revenue increase requested represented through a rate case proceeding, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysOriginalRequestedPercentReturnOnEquity
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's original requested amount of increase (decrease) to existing rates for 2011, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysOriginalRequestedRateIncreaseDecrease1
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The entity's original requested amount of increase (decrease) to existing rates for 2012, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysOriginalRequestedRateIncreaseDecrease2
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The entity's percent of shortfall which can be included in an additional rate adjustment in the next year, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysPercentOfShortfallWhichCanBeIncludedInAdditionalRateAdjustment
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's requested value established on which the entity is allowed to earn a particular rate of return on operations, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysRateBaseInOriginalRequestedRateIncreaseDecrease
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The rate increase (decrease) approved for implementation in 2013 by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysRateIncreaseDecreaseApprovedForImplementation3
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The rate increase (decrease) approved for implementation in 2014 by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysRateIncreaseDecreaseApprovedForImplementation4
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The entity's implemented rate increase (decrease) to existing rates for 2011, approved by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysRateIncreaseDecreaseImplemented1
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The entity's implemented rate increase (decrease) to existing rates for 2012, approved by the applicable regulatory agency.

No definition available.

Name:	psco_EntitysRateIncreaseDecreaseImplemented2
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Entity's rate of return on equity requested by a party (or parties) independent of the entity, as part of a rate case proceeding, filed with the applicable regulatory agency.

No definition available.

Name:	psco_EntitysRateOfReturnRequestedByWholesaleCustomers
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The first amount of margins on hybrid Renewable Energy Credits (REC) trades to be shared approved by the applicable regulatory agency.

No definition available.

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

The percentage of margin associated with stand-alone Renewable Energy Credit transactions which will be shared beginning in 2011 as determined by the applicable regulatory agency.

No definition available.

Name:	psco_InitialPercentageOfMarginAssociatedWithStandAloneRecTransactions
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The entity's maximum amount of property taxes that will not have deferred accounting treatment, approved for implementation by the applicable regulatory agency.

No definition available.

Name:	psco_MaximumAmountOfPropertyTaxesNotSubjectToDeferral
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The maximum percentage of margin associated with stand-alone REC transactions which will be shared by 2014 as determined by the applicable regulatory agency.

No definition available.

Name:	psco_MaximumPercentageOfMarginAssociatedWithStandAloneRecTransactions
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The maximum percent return on equity used in an earnings test in the entity's rate regulatory proceeding approved for implementation, filed with the applicable regulatory agency, in which customers and shareholders will share weather normalized earnings based on three ranges.

No definition available.

Name:	psco_MaximumPercentReturnOnEquityUsedInEarningsTest
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The minimum percent return on equity used in an earnings test in the entity's rate regulatory proceeding approved for implementation, filed with the applicable regulatory agency, in which customers and shareholders will share weather normalized earnings based on three ranges.

No definition available.

Name:	psco_MinimumPercentReturnOnEquityUsedInEarningsTest
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The 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_PercentageOfMarginOnHybridRecsApprovedForFirst20MillionOfMargins
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The 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_PercentageOfMarginOnHybridRecsApprovedForMarginsInExcessOf20Million
Namespace Prefix:	psco_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The percent return on equity between the minimum and maximum percent used in an earnings test in the entity's rate regulatory proceeding approved for implementation, filed with the applicable regulatory agency, in which customers and shareholders will share weather normalized earnings based on three ranges.

No definition available.